Timeframe? Interests for activities and stops? Preferences for campground amenities?
Absent any specific destinations, I prefer taking 86/88 across New York to taking I-90 across and contributing heavily to the New York state highway coffers. Parts of I-86 especially were at one point very rough, but I think most if not all of the terrible bits have since been repaved.
For possible destinations, I've thoroughly enjoyed Knoebels (Elysburg, PA, probably somewhat out of your way) and Letchworth State Park (NY, betwixt Rochester and Corning), obviously for different reasons. The Knoebels campground is nothing special, aside from it's location immediately adjacent to the fantastic traditional amusement park. It's clean and decently run, but rather cramped (particularly in the US states section) and low-frills. The location makes up for a lot!
Letchworth state park is spectacular, with many varied hiking/strolling and picnicking options in a spectacularly beautiful setting. The campground area is nice with typical state park luxuries (or lack thereof): simple but functional showerhouses, gravel sites with some space between them, partial hookups, etc.
Vermont certainly has some neat areas and parks. The state park campgrounds are all on the primitive side (no hookups), and some have many rather small or hard to access sites. Some do have very pretty settings, and the ones I've stayed at have all been clean and well-kept. I would suggest making reservations for stays on weekends, especially given the size of your trailer.
The Shelburne Museum is worth spending a day or two exploring. There are many great hikes, bike trips, and places to go boating here.