Love this thread concept and hope it keeps going.
I think Plymouth somehow manages to fly under the radar, but it's actually a great spot to stroll. As disappointing (silly, even) as Plymouth Rock is, the waterfront is very pretty. There are places you can access the harbor, and plenty of docks and piers you can peruse as well. And it's only a block or so to Main St. which is charming enough with plenty of shops/restaurants. If you're a beer drinker, it has a nice cluster of breweries downtown - Vitamin Sea's new location (with a patio overlooking the harbor), Sour Not Sorry, and Second Wind all have taprooms within a 5 minute walk of each other.
I'd add Littleton, NH to the list. A great Main St. with some decent restaurants, bars, shops, etc. Schilling is worth it, even if you're not a beer person, just for the pizza and the views of the river and covered bridge. It's housed in a historic grist mill right on the river as well. There is a pedestrian covered bridge and a suspension bridge, so you can check out the river (and even walk onto the rocks) if you're feeling a bit more adventurous.
I'll shill for New Bedford as well. For all of the issues that come with being an old mill town in MA, downtown New Bedford is actually charming (it was largely developed as a seaport before the rise of industry). A good chunk of it is a
national historic park and it has some
impressive architecture and quaint
cobblestone streets with
galleries, restaurants, shops, etc. You can cross the street and
check out the fishing fleet, eat at one of the waterfront restaurants and see the Schooner Ernestina too. The
Whaling Museum is fascinating and interactive for young ones as well. It's too small of an area to plan a weekend around, but it's certainly a good place to spend an afternoon or the day.