What a great adventure OP.
Since a lot of Canadians travel throughout the US and have a different perspective well two of the friendliest states that I drive through are West Virginia (I would say ironic given last week's disgusting news but I don't want to get points) and Virginia - the service with a smile and warmth is exquisite.
I love Southeast Virginia. The area around Williamsburg, just beautiful. I am assuming there are a lot of bylaws for signage, building structure, urban sprawl because it is just lovely. But the 64 can have a ton of traffic going in and out of the area. Unsure how that affects daily living, maybe not at all.
Also, I know you said town but Burlington, Vermont is a very livable small city. Stowe is beautiful and quaint.
There are towns on the islands of Lake Champlain that are quaint as well.
I concur about North Conway. Spent a lot of my youth hanging out there. I went to university in Quebec near the NY/VT/NH/ME borders. So many beautiful towns. We loved a road trip.
Lake Placid is nice.
I would also look to coastal towns from Maine, NH, MA and down if being near the ocean is a great addition. Even on Long Island, if one has the money, there are some beautiful towns. I love Sag Harbor.
Again, if money isn't an issue there are some really gorgeous spots on the Hudson, north of NYC.
Northern Michigan is gorgeous.
(I have travelled in many other areas of the US as well but New England is a great choice for your criteria and Virginia being high on my list of friendliness. Also, for me I would really look to university towns.)
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Up here, this city girl has a town she loves in the Eastern Townships of Quebec - North Hatley. On a lake, with a myriad of bike paths and gorgeous architecture. You can see the colonial influence. Absolutely picture perfect.