For me it's all about the mountains. The catskill mountains are beautiful any time of year. There is a little town near by called Wood Stock. It's like time stopped in the 70's there. The people are very laid back, friendly and very much into the art scene, mostly retro.
Then there are the Adirondacks. Beautiful lakes , small towns catering to tourists and many places to rent a cabin for the weekend or an entire season. If you're a nature lover you can't go wrong either way! If you're into festivals there is a Rennisaince festival every year in Sterling NY. If you're into wineries , there are some great places to check out near Watkins Glens, along with some beautiful falls to wander around. These are just but a few things, but I hope I have given you an itch to come visit upstate NY:-)