personally i think tent camping is the way to go..
been there, done that (02 and 03). NO question about it, RV is a million times better. You can sleep til noon in the AC, which means you can last through all the late nights. I highly recomend an RV if you can afford one. I won't go without one.
Also, if you rent Cruise America, they have mechanics onsite at Bonnaroo b/c they have so many RVs there. Good thing to know. I had some friends rent from a local distributor and their RV broke down during the 05 Roo and it never worked after Friday. If you have a problem with a Cruise America RV, call the hotline, they send the mechanic right over.