Skidmore Stables (SMBA) have some gnarly singletrack XC.
Luther Forest is off of exit 12 in Malta, has some pretty mellow xc trails. I work right there so it's good for a low-key evening rides.
Moreau state park has some trails there, but they're pretty gnarly. Steep climb, some single track at the top, then a gnarly downhill. I haven't been personally, but may be taking a night ride there on Wednesday.
Don't even bother with Gore. the DH trails there are terrible.
Oak Mountain in Speculator is working on a bike park now, don't think it's open to the public yet, but looks pretty promising.
http://vimeo.com/47608069
Head farther North and the Lake Placid/Wilmington/Whiteface areas have a TON of xc, bike parks, and of course downhilling at Whiteface.
If you're strictly looking for a DH session, Plattekill is probably the way to go. $35 a day, I believe.
Or, if you want to venture over to Vermont, you can get Pine Hill in Rutsvegas, the Green Mountain Trails if you like long climbs (~1K vert) and then heading right back down. There is a road up part of it, so shuttle laps may or may not be viable. Milestone, STAB, and Burke all have some good XC/DH stuff, or Killington for some lift served DH.
