Every year we try to go to:

Winterhawk, New York, mid-July, which has a web site: http://206.100.237.27/winterhawk/

Thomas Point Beach, Maine, Labor Day weekend: http://www.thomaspointbeach.com/bluegrass.html

Pemi Valley, New Hampshire, early August (web site out of commission)

Strawberry Park, Connecticut, early June

Noppet Hill, Massachusetts, July

and whatever other bluegrass festivals we can squeeze in. The jams are always phenomenal, the people are wonderful, the shows are great, the lifestyle is just amazing. I've never been to a folk festival, but friends tell me they are also great. By any means, get to a few acoustic music festivals. Most of them have web sites.