I did Rangeley through the mountains to st johnsbury vt. It was very nice. Slow winding rd with great views. I think it was rte 16 and then 110 maybe? I'll check my log and try to get the exact route. I think you can pick up the same route from Portland if you go up rte 302 you can get to 16 somewhere around Conway NH......We stayed a few nights in the Keene NH area....Swanzey lake campground. Nice "woodsy" place.
Do you have your schedule set in Niagara Falls. If your interested let me know. Not sure what you like to do, but can give you some sugestions if you like.
There are many different CG along the way. If you take the northern route (highway 2). You can cross over to NY at the north end of Lake Champlain. You could then head towards Malone NY following the river to Interstate 81 go south to I90 then onto Niagara Falls. This is a slow winding highway with lots of scenery. In NH you could visit the Ben and Jerry's ice cream factory.
__________________
Terry and Janet
2008 3001W Windjammer
2007 Ford F150
Make sure you cross over and see the Canadian side of the falls and go through to Niagara on the lake, a nice drive and a nice touristy town to walk around.
If you just need to put your head down you can park in one of the lots at the Seneca casino in Buffalo, NY and you are a short drive to the bridge over to Niagara Falls, on.