Located in the gorgeous Vermont hills overlooking Lake Willoughby, Sentinel Rock State Park is named for the iconic glacial rock perched in the middle of the park. Encompassing 356 acres, it's a good place to watch sunsets, and explore some fine hiking trails through the woods. And Lake Willoughby is a beautiful lake with clear water and a beach.
If you go:
Open all the time, with no admission charged. Rather limited parking area, but usually quite adequate, as the park is generally not busy.
Links:

Hinton Hill Road
Westmore, Vermont 05860 USA
parks@vermont.gov
Mailing address:
Vermont State Parks
1 National Life Drive
Dewey 2
Montpelier, VT 05620 USA
Phone Numbers:
Vermont State Parks
+1 (888) 409-7579
+1 (888) 409-7579