I'm re-posting this useful tidbit from Terps:

there are TONS of other fests u might want to check out too.

10,000 lakes festival (northern Minnesota)
Coachella (Polo feilds in south cali)
Bonnaroo (a 200 acre farm in manchester Tn)
Lolapalosa (Downtown chicago)
Summer camp (chillicothe IL)
Wakarusa (Lawrence Kansas)
Langardo (Southern florida)
Red rocks (In the mounts of colorado)

I had to nuke the post though.