I went for many years - in its early years in Cazenovia, later in Morrisville at the State College. Always for just 1 week; once for two and I wouldn't do that again - too long for me.
I've not been since it was sold and moved to Auburn. It's gotten way too expensive for me. If you can afford it - it can't be beat: faculty from around the world, best show I've ever seen and great vendors.
http://www.quiltingbythelake.com in 2013 will be 7/15-7/19 and 7/22-7/26