We went to both last year, and had a wonderful time at each. Letchworth has a great pool and some spectacular hiking. Also not far up the road in Perry NY is the Charcoal Coral a cool place for those with kids. It has a restaraunt and mini golf and the such. Some nights they have a stage show. Also has a twin drive in. Not much else to do around Letchworth. Watkins Glen also has a great pool. WG has the glen that is a cool hike with waterfalls. You can drive the wine trail and also the racetrack if you are into that. When we went last summer there were no sanctioned races but we had a great time at the track watching different cars testing and tuning. Both great choices. Also went to Jellystone in North Java the year before and there was tons for the kids at the campground which is typical of all Jellystone parks. The waterpark was first class but this place was seriously in the middle of nowhere.