We go to the Glen every year fo the NASCAR race as well as other times. There is a restuarant in town called Savards with great breakfasts--blueberry pancakes, yum! We also like to go to a flea market type place called the Windmill in Penn Yan. It is open only on Saturdays. There are local foods, a great basket booth, nice amish furniture on display, all sorts of things. I guess similar to alot of others, but we love it. Try the salt potatoes, small new potatoes steamy hot with salt and butter.
Watkins Glen State Park also has a campground, one of the most reserved on Reserve America. We camp at the track for the race and other times with stay/camp friends who live in Burdett, along the east side of Seneca Lake. A ride up Rt 414 has beatiful views of the lake and vineyards. Lots of wineries and a few micro-breweries. There is a campground in town right at the base of Seneca Lake run by the town of Watkins Glen, right near Walmart. The latter has only there for a few years but very convienient as they sell food also, unlike the ones nearby us in Jersey. Prices at Walmart for food stuff are much better than the supermarket in town. If going out to dinner there is a place called Johnson's in Hector/Burdett/Rt414 which is a real hole in the wall only locals frequent that has wonderful prime rib. About 10 min from town, turn on 4th st east toward Walmart and drive up the east side of the lake to Rt414. Seneca Lodge is famous but dinner a bit pricey, if you can, check out the bar though, it is interesting.
Also, try to get a local map from AAA of the Finger Lakes before going. As you approach Watkins Glen on Rt14 there is a turnoff for Johnson Hollow Road on the left which will bring you up near the KOA on Rt 414 without going into town, up a HUGE hill and basicly back tracking to KOA. I think it's right by an American Legion or VFW Post, a left turn from Rt14.
The ride up is better on Rt 17 thru NY than on Rt 81 thru PA which is a lot of long upgrade hills. You can get to Rt 17 from Rt 287 to NY Thruway for one exit to Harriman from NJ. Have fun and hope you like it as much as we do!