I had no idea where I was going - it was pretty much random. I was 18 and doing a summer working 'soccer' coaching at a summer camp in the Catskill Mountains - upstate New York. A mate and I had 2 or 3 days off, and a couple of American lads who worked in the kitchens, said they were going...
Quite a list.
I've been to pitifully few. I did however, go to this: http://en.wikipedia.org/wiki/Woodstock_1989
Although my recollections of the specifics, are a bit VAGUE.