While I haven't done this event, I am a veteran of four Clycle Oregons ("COs"), which is similar in nature to CGY, only on steroids since if it sells out (which it usually does) there are over 2,000 riders. I have also done a few other supported tours.
Any wait for a shower will depend primarily on two factors. The first is how many showers are available. CO typically uses shower trucks, and they have a decent number. I cannot recall off hand whether there have been times when school gyms have also been available some nights. The second factor is timing. If you go to shower during popular times, there may be a wait. With a sherpa service, you will have more flexibility. I you arrive at camp and see that there is little or no wait for a shower, you can grab your off bike clothes and head on over without having to spend time setting up your tent. The times when I have had to wait, it's never been more than 5 or 10 minutes.
As alluded to on the web site section about sherpa service, a big in-camp noise issue is snoring. Personally, snoring drives me crazy. It's even more problematic in sherpa service areas since the tents are usually placed very close together and you usually sleep next to or near the same people during the entire trip. I did the Bon Ton Roulet again this year. One night we happened to camp next to an extremely loud snorer. If you don't sleep like a rock, ear plugs are essential. If there are porta-potties near your tent, they can also screen out the loud bangs that happen when inconsiderate people let the doors slam in the middle of the night. Finally, they help with tent zipper noises.
As for laundry, I usually don't boher washing off-bike clothes unless they are synthetic. It's a week, and it's not a beauty contest. I don't mind a little dirt. As for cycling shorts and jerseys, I wash them while taking a shower and then leave them out to dry. Three or four sets is enough to get me through the week. CO also has wash bins for you to hand wash stuff. CGY looks pretty well organized. Wouldn't surpise me if they have the same.
In general, I would say that if you have a low tolerance for little things that might annoy you from time to time, like having to get out of your tent in the middle of the night to use a porta-pottie as opposed to having a bathroom a few feet from the bed, you might want to stick to hotels.