Ok I'll take a shot at a few things. First, one way rentals are possible, but can be very expensive, so look into that. Some companies will charge you a per mile fee if you do not return to the same location. Since you asked such a broad question I'm going to assume you've never been to Quebec or the northeast and base recommendations on that.
Quebec is a beautiful city. Very walkable (assuming you mean Old Quebec). I recommend this hotel for both location and price. PM me and I can likely get you our corporate rate.
https://www.hotelsjaro.com/palace-royal/ Park your car and spend a few days walking the streets, forts, museums, restaurants, etc. It's like going to Europe w/o leaving North America. I've never been to Nova Scocia. Another favorite city is Portland Maine. Again a very walkable old city on the water. Cobblestone streets, great food and breweries. Stay within walking distance to the old port and you can't go wrong. There are some sightseeing boats or you can go out on a working lobster boat. Great stop for a couple days. Boston is a great city, but like any major city, pretty expensive to stay. The subway system is old, but works and is not hard to navigate if you want to stay on the outskirts. A couple good to-do's are:
https://www.woodmans.com/about/the-story-of-the-fried-clam/
Allegedly invented the fried clam and harvest them in the waters out back of the restaurant. Can't go wrong for any seafood there, but the fried clams are a must. It's just north of boston so you might want to stop there on your way. (Needless to say order whole clams not strips!!)
In Boston make your way to
https://faneuilhallmarketplace.com/
lots of restaurants, shops, street performers, etc. You can also pick up the Freedom Trail which is a marked walking tour you can do yourself or with a guide through some very historical places.
https://www.thefreedomtrail.org/
Whether you walk the trail or not, please visit the USS Consitution. An amazing an unforgettable experience.
https://ussconstitutionmuseum.org/
Near Faneuil hall are some very old cool taverns, some of the oldest in the country. You'll know them when you see them. A favorite is
Union Oyster House, Boston, MA :: Seafood and History at America's Oldest Restaurant
Walk around the few surrounding blocks and eat and drink! Stay away from the many bars called "Cheers"
That's all for now. Happy to provide more details or suggestions once you narrow your itinerary to more than "northeast"!