In no particular order: I would say that one good thing to do in Dover Plains is picnic, and I ought to know because I've done it probably dozens of times over the years. It's a pretty peaceful environment for such a thing with a lot of greenery.
Another seems to be hiking; for example, the Dover Stone Church seems to be a big draw for locals and people outside the area with an interest in such things.
Fishing is probably another one of the better things to do outdoors in Dover Plains, though as I've mentioned elsewhere, the only place I know for absolutely certain that it's allowed is a membership-only preserve in town. Still, there have to be other spots to fish here, such as ponds and spots along the Ten Mile River. Just be sure you aren't trespassing on someone else's property.
Dining out has to be on this list. There aren't a ton of places to eat in Dover Plains, but there are a couple, and some of them are pretty good as far as I'm concerned. These restaurants account for a good bit of whatever social life this village has.
Finally, as corny as it sounds, I'd say relaxing and living easy is a pretty good thing to do in DP. It's a quiet area for the most part and lots of people who are fond of simple living likely choose this town for just that, so it makes sense.
