Why not just go to Cape Cod?

I'd recommend LBI in New Jersey -- you can come into NJ and get on the Garden State Parkway. From there it's about 2 hours south of Manhattan and an hour or so east of Philly -- it'll make the last leg of your trip nice and short! The nightlife isn't wild, but there are plenty of great restaurants and bars, and shopping in Beach Haven. The hotels on the beach definitely fall into the "motel" variety, although there's a boutique hotel a block off the beach called Daddy O -- a little pricey though. www.daddyohotel.com

Block Island, RI is a little out of your way, but very cute and walkable. Take the ferry from Point Judith (you can even leave your car in a lot there). If you take the car on the island, I think you can then take a ferry to the eastern tip of Long Island - or to New London, CT - and continue your drive back that way.

Otherwise, I'd suggest the CT coast. I don't know of specific town's beaches, but Mystic, Westport and others have cute towns.

There's an exit on I-95 in CT for the Thimble Islands, just east of New Haven. I've always been curious what they are like!

I should have said that Block Island is out of your way because you would be a little farther east than the interstate you would normally take to get from Boston to NYC/Philly. But it's definitely in your general direction home, and not difficult to get to!

I vote for Newport RI. Gorgeous town with lots of shops and restaurants.

I'll second Newport too. It was chilly when we went, but I kept wishing it was warm so we could lounge on the beach! The downtown area is loads of fun, too. I would recommend a hotel in that area so you can walk to nightlife, because the drive to the beach is quick 'n' easy from just about anywhere.

I love Newport, but I don't think of it as a "nice town with hotel/motel on beach". It's a great eating and touring city--and pretty darn pricey in the summer. It's also relatively close to Boston--does that matter?

Tak a look at some of the towns in South County Rhode Island-
around Westerly. There are some motels directly on the beach and B&Bs and inns and some are more upscale.The Watch Hill part of Westerly has a few nice streets to walk around adn more beach access

Easy access to/from rt 95 for the way home

I agree with janie, especially since the OP said "not looking for nightlife", so IMO that cuts out Newport.

South County RI is beautiful. I really liked the beach at Misquamicut the one time I was there.

ggreen,
The thimble islands are amazing. Get off at exit 56 and drive south. The tours are about 10 for 45 minutes, they are great!

Thanks tinyteacup! I'll be headed up I-95 later this month for a girls weekend in Newport, and I'm always looking for a good "pit stop". I'll be sure to check them out!

I would recommend Watch Hill in Westerly - the beach is right there and there are restaurants and shops. You can also eat and walk around in downtown restaurant. 99 High Street is a great restaurant downtown.

You might want to check out Madison, CT. Very cute town. Well, beautiful actually.

Just FYI, the OP was from June and her trip has long since passed. In my post from that time, I mentioned that I'd been curious about the Thimble Islands; tinyteacup was responding to that. Not that the recently provided info might not be useful to someone in the future... but probably not relevant at this moment!