There are basically 2 ways to go through the Grand Canyon on the Colorado river - using a private permit or on a commercial trip. A private trip means that you get together a bunch of people (including someone who's been through the GC before and at least some experienced river people) and after you are granted your permit you have up to about 20 days from when you launch to make it through the canyon. The private trips we ran into on the river this month applied for their permits 11 years ago, the current wait is 25 years (though so many people die while on the list that the actual wait time may be a mere 15-20 years). There are a whole bunch of commercial companies offering trips and there doesn't seem to be that much difference between them; the wait time for a commercial trip is anywhere from a few months to about a year for the more popular companies such as AzRA. The main options are motorized vs. oar rafts (the companies supply the strong arms to do all of the rowing, though you can volunteer to help out); some companies also offer an option to paddle your own boat (though those are known to flip a lot). A motorized trip takes about 7 days with around 12-20 people per raft, an oar trip usually takes 2 weeks and an oar boat usually holds 3-5 people (plus the guide); other than the trip length, the main difference is that an oar trip is quiet - the engine noise on a motorized raft is quite significant (and IMHO fairly disruptive). Some companies also offer "special" trips, for example AzRA runs a few hiker specials every year that use a motorized boat but take 10 days (with some days spent entirely on land, hiking). Another twist is that you can hike into the canyon and join a trip near Phantom Ranch and ride it down the lower canyon, or put in at the top of the canyon and hike out when you get to Phantom Ranch (the entire length of the canyon is 225 - 250 miles depending on where exactly the trip ends, some trips go all the way to Lake Mead). As I mentioned above, I went on an Arizona Highways photo workshop trip; the advantage of doing this was that the wait time was quite short and the trip was tailored for taking photos, the main drawback was a much higher cost (standard cost for an AzRA trip is around $2K whereas the photo workshop cost over $3K) - part of the reason for the higher cost was that AzRA sent a second raft with us to haul all the photo equipment we had. Our trip had 3 professional photographers (including the leader - Jack Dykinga - one of the best landscape photographers of our time); the rest of us spanned the spectrum from very serious / advanced amateurs to spouses with no interest in photography. I was the youngest person on the trip, the oldest folks were in their 70's (I noticed that most of the other trips generally had younger people, I think it was the photo workshop aspect of our trip that attracted all those geezers).

The water in the river comes from the bottom of Glen Canyon Dam, which means that it's extremely cold all year; in our case, it started in the low 40's at the top of the canyon and by the time we were leaving at the other end it had warmed up to low to mid 50's. If you sit in front of the raft you will get splashed quite frequently and unless the air is really hot it's no fun getting drenched in 40-degree water, so most people wear some kind of a water-proof outfit (I wore a bright yellow plastic outfit and quickly acquired the nickname "Duck"). If you sit in the back the splashing is fairly minimal but I also think the experience isn't as good there, so I spent about 90% of the trip right up front (getting wet all the time). The air temperatures can vary quite dramatically - the main season runs from May through September and apparently it's not uncommon to have sleet and snow at the beginning of May trips (the canyon gets warmer as you float down river). In our case we had fabulous weather, with air temps ranging from 60's in the mornings through 80's - 90's in the afternoons. In June the temperatures start rising and days are longest; in July and August the weather is at its hottest but during that time the monsoon season also brings frequent rains and storms. It sounded like September was possibly the best time to go - the weather is almost guaranteed to be nice but not too hot, the only major drawback being that days are getting shorter.

As far as the logistics of the trip, I'll describe what happened in our case (this was an AzRA trip) but from what I understand the arrangements are pretty standard so you can pretty much expect a similar experience with any commercial company. The night before our departure we were given a book describing the river, a coffee mug, and they explained the procedure to us - everyone has a white waterproof bag for things needed during the day, a blue bag which is not accessible during the day (only in camp), and a blue bag with the sleeping unit (which contains a sleeping bag, a pad, and a bed sheet). They also provide canvass bags for beer and other drinks people may bring with them, the recommended max was 24 cans but many of us far exceeded this allotment by a big margin. In the morning people transfer a few beers into a common bag that is left in the water where it stays cool. The crew cook breakfast every morning (hot tea and coffee, fruit, bread / bagels / sandwiches / etc), lunch is usually a relatively simple affair (make your own sandwich being very popular), and dinner is an elaborate meal cooked in camp. The day is spent sitting on the boat watching the scenery go by (with the guide explaining the geology, history of canyon exploration, and so on). There are regular stops for hikes into side canyons, to see waterfalls, and so on. In the late afternoon the crew will start looking for a suitable camp (which is easier for smaller trips, as some sections of the river don't have many large camp sites and they do fill up). A typical camp site will be a sandy area on the bank of the river, with a bit of tree cover (and yes, the sand definitely gets into absolutely everything - even places / orifices where you wouldn't necessarily expect it). The passengers are asked to help unload the bags from the boat and then generally scatter around, finding their preferred place to spend the night; some people bring or rent tents but unless it's raining (or one needs extra privacy) it seems hardly worth the trouble; I rented a tent from AzRA but in the end never even considered using it, sleeping under the stars was so much fun. While everyone is pitching tents or exploring the surrounding area, the crew is busy cooking dinner and this is usually quite an elaborate meal consisting of several courses; folks are encouraged (but not required) to help prepare dinner (the reward usually being some kind of an adult beverage). Because the canyon has steep walls in most places, it gets dark pretty early and so most people go to bed very early (on our trip we often got up super early to be in photo position for sunrise, so going to sleep early was not a big problem). All peeing simply goes into the river (which means that everyone does it wherever they feel comfortable), for "number 2" a device known as "groover" is employed when in camp (it used to be a box with bars on top which imprinted grooves on people's behinds, thus the name - it now works a bit differently, butts are no longer marred). The important thing about groover is that once it's packed when you leave camp in the morning, it's not available at all until back in the next camp in the afternoon / evening. Thus many people drink a lot of coffee in the morning so that they will have finished their stint on the poop throne by the time the "Last call for groover!" scream is heard throughout camp. If one has an urgent need to do the other business while on the raft (and can't wait for a pit stop), one has to stand on the back of the raft (next to the engine) and pee overboard. I did this a few times and it's an interesting experience, esp. when other rafts are following closely behind the vessel you're on. There are strict rules regulating things like human waste and litter and the crews are extremely careful to leave as little trace as possible (to the point of collecting and removing any sand that had coffee spilled on it).

After about 2-3 days on the raft I started wondering if perhaps a week plus would be too much, so I asked our guide about this and he said that this was very common - people get a bit bored / restless after a few days, but when they get to the 4th or 5th day they never want to leave. I was quite skeptical about this, but it turned out that he was dead on - on the 4 - 5th day I didn't want to ever leave the canyon (and next time I'm definitely doing a longer trip). There are no phones, newspapers and generally no contact whatsoever with the outside world while on the river, just wildlife and the occasional fellow raft, and after a few days everyone gets in tune with the river / canyon, great camaraderie develops, and soon you just don't want to leave. We did get mooned by quite a few trips but unfortunately there were too few folks on our trip willing to return the favor so we merely watched.

The nature of the river changes quite a bit depending on the water flow which is entirely controlled by the dam. During our trip the flow was about 10,000 cfs which is basically what it was when Powell first ran the river in 1869. Generally the flow from the dam is higher during the day (since there is higher electricity demand) than at night, and depending on where you are on the river this is shifted by the amount of time the water takes to travel. For example, Phantom Ranch is about 24 hours of flow from the dam, so it gets roughly the same regime (more water during the day, less at night). Before the dam was built the flow sometimes exceeded several hundred thousand cfs; with the dam in place the highest flows (which max out around 60 - 80,000 cfs) occur during a power emergency, one of the bigger ones happened in 1983 when flow was increased to flood levels and Park Service helicopters flew through the canyon dropping notes on rafts telling people to select camp sites high above the river. The flow doesn't just affect the level but also changes the nature of many of the rapids, the guide books have ratings that tell you how nasty each rapid is at different levels (and the relationship is far from simple, some rapids get much worse when water flow is low, etc). Some of the larger rapids were certainly quite exciting, but I never felt any danger at all; boats do flip, though, and people drown every once in a while, so some danger is certainly present.