Ok Ive been to all of these so check out.
NY: http://www.lakegeorgeescape.com/the-park/resort-map/
NH: https://www.danforthbay.com/
ME: https://koa.com/campgrounds/bar-harbor-oceanside/
Each rv park has to much to do for the kids. In NY tubing down the Scroon River. Free shuttle service to down town lake George. Danforth Bay in the White Mountains activities all day for the kids and get in you rride and explore the White Mountains. Yankee BBQ offers the feast for 4. In Maine Bar Harbor has a guy cooking lobster dinners on premise and also has free Mountain explorer shuttle service around the island.
We would go back to each of these again without hesitation. Happy Trails