I haven't been to Bonaroo the past two years, but I went the 4 years before that. It's an amazing experience to say the least. If you've never been to something like roo before, the sheer size of the place will blow you away at first. The only festival I'd been to before was HFStival, and after going to roo, I wouldn't call HFStival a festival.
When you enter the grounds, they will do a very thorough search of your vehicle. This obviously is to search for illegal items, but also for any non roo-approved items. I've seen numerous arrests right there, and piles upon piles of stuff that's been cast aside because it's not allowed in. This is all up to the decision of the person checking your vehicle. Some of them are laid back and let things go, others are sticklers for the rules. Do yourself a favor and read up on the rules, and then you can decide what you want to risk.
After that you'll get your tickets validated and be assigned your camping spot. I've never figured out the formula for the assigning of camp spots, but I think it has to do with what cycle the moon is in, if mars is aligned with venus, whether the Red Sox beat the Yankees in their last meeting, and then that all gets thrown out the window and the person just picks a spot for you at random. I've shown up there hours before the first performance and gotten a great camping spot close in, and then other years have shown up a day and a half ahead of time and gotten a crappy one where I had to walk about a mile just to get to the stages.
The "parking lot" is also the "camp ground", so do yourself a favor, as soon as you get parked, break out that tent quickly and anything else that you'd have to space out your actual camping area. They will park those cars in tight, and you want room to maneuver. Some years they have had it where you're expected to camp in front or behind your vehicle and they space out the lines enough so that there's room in front or behind the vehicles, others, they expect you to camp to the side and they do two by two parking with space enough to the side for a tent or two. Again, not sure what the deciding factor is on this one, but just be ready for both because experienced rooers will have that tent out before their car is even parked so that they get all the space they can. It's easier to give up tent room you've taken up then it is to move all the cars to give you more room.
Once you're all setup, it's time to enjoy the festival and all it has to offer, and believe me it is a lot.
A few suggestions:
1 ) Patience is a virtue at Bonnaroo, there's lots of lines, lots of waiting.
2 ) Make sure your AC in your vehicle works. Arrival day you're guaranteed to be in a backup to get into the grounds for at least an hour, I've been in it up to 4. They actually create an "exit" directly off the interstate into the grounds.
3 ) Once you're setup, make friends with the people camped around you. They will be your neighbors for the time you're there and I've found it's always best to be amicable with your neighbors.
4 ) Always have water with you. It's hot, it's dry, and you'll want to stay hydrated.
5 ) Have comfortable footwear, you're going to do A LOT of walking.
6 ) Unless you want to pay the $7 for each use, be prepared to not shower for a few days, and be prepared to be around a bunch of people who aren't showering.
7 ) Not all the fun is inside the festival grounds themselves, explore the campgrounds, there's lots of fun vendors out there.
8 ) Leaving the festival is a bigger nightmare then getting in, keep your fingers crossed that the people camped around you want to leave before or around the same time you do, otherwise you find yourself blocked in with no place to drive.
Do yourself a favor and look over the FAQ on the Bonnaroo website -
http://www.bonnaroo.com/faq.aspx
Here's a sample map of the layout including campgrounds -
http://www.tennessean.com/graphics/SPECI...4/map1.gif