Each person has to pay for a camping wristband if they plan on camping in addition to their festival ticket/wristband. Festival ticket prices tend to stay fixed as it's part of the festivarian spirit not to scalp tickets. RV camping requires an additional vehicle camping pass- I'd suggest just tent camping but that's just personal preference (and I don't own an RV)
The past several years I've camped at the Mary E Illium campground. Here are some pros and cons:
Pros:
The only campground that allows firepits
Has trees and thus lots of shade (so you don't wake up baking in your tent in the AM)
Has an awesome but frigid river (for bathing if you can stand the cold and have biodegradable soap)
Cons:
Its the farthest away from the Festival (9 miles I think)
You have to stand in line with all your stuff and wait for the buses (depends on what time of day you want to go to the fest, but I've waited for a very long time)
Because its the farthest away from the festival, you pretty much have to take everything you need for the entire day (and evening) because you don't want to make several trips
That being said, it seems that Town Park and Warner Field are probably the best campgrounds, because they are right at the Festival, but tickets can be hard to come by. This year I got lucky and got picked for tickets for TP :-)
Of the other two campgrounds, they are both in open so you will wake up roasting in your tent in the morning (fair warning about that one). One is family camping which is good if you have kids- quiet hours at night, less partying, etc. and it's close to the high school so you can take hot showers.
The other (lawson) is a baseball field with lots of tents in the open.
Illium is your best bet (IMHO) and just be prepared to wait for the buses in the morning and you'll have a great time!
Others please feel free to provide additional feedback or corrections :-)
Listening to:
mumford and sons