While we were in Long Island City I suddenly remembered that I'd read about a pedestrian bridge leading from that neighborhood to Roosevelt Island, and it happened to be about three blocks from where we were standing. Which seemed like too good an opportunity to pass up.
It seems that there's not a whole lot going on on Roosevelt Island though. You can pretty much expect find a nice park, views of other land masses, apartment buildings, a grocery store, and a hospital. I think there's a library too. We only walked to one end of the island so maybe all the cool stuff was in the other half. (I'm not curious enough to want to go back though.)