Pretty close by rt 22 in between 684 and Copake Falls is the (longer) southern portion of the
Harlem Valley Rail Trail. (asphalt, perhaps not as pretty as the northern section)
Last time I checked, there was also a bike shop with rentals at Copake Falls next to the bike trail. In summertime the state park also sort of like an old-fashioned swimming hole -- where I made my first attempts at swimming when I was like 5 years old. Not far south of there is Rudd Pond, which has larger swimming.
The low trail from the west side into Bash Bish Falls seemed pretty fun when my parents took me there several times starting when I was around 5 years old. But it's been a long time since I've done it -- now I usually go there in the middle of long bike rides, so I save time by riding farther east higher up the road to where there's a shorter steeper trail to the falls.
There's also lots of quiet roads to explore around Copake + Ancramdale. It's an amazing area. Leave the kids home. Go there for yourself. Sharon and I would be riding there tomorrow if it weren't for the rain and wind.
Ken