I grew up on the coast, and I'm accustomed to many US beaches, particularly in the south. Recently I found the most dramatic beaches may be those of the outer cape along Wellfleet and Truro.
Boston Harbor Cruises & Baystate Cruise Company), especially since it is easy to carry bikes on board, even cargo bikes fit easily. The corners getting on the ferry and through the ferry cabin are tight and require some rear wheel lifting, and the gangway in P'Town is on the narrow side. I've heard that a loaded Longtail will fit, but I'm not sure about a Workcycles Bakfiets. All in all very doable and easier than getting a cargo bike on & off the Downeaster.
But once Shore Road leaves the shore it becomes very hilly and remains so through Truro and into Wellfleet. When riding an overloaded cargo bike (or with a kid and a full basket) the ride becomes more work and less fun. There are no mountains on the Cape, but don't let the hills on the outer Cape fool you, they are steep and relentless when it comes to casual touring. I haven't found a flatter route, which is frustrating since there once was a railroad to P'Town, much of which is now a rail trail. But that flat route across Truro was dissected by homes.
Worse than the hills was US 6, a four-lane highway that provides the only link through Truro. This is a one mile section along US 6 from Shore Road to Castle Road, with no parallel route. Despite the generous shoulder, this one mile of cycling with uncomfortably fast traffic sucks all of the enjoyment out of the bicycle ride. We won't cycle to Truro again until we find an alternate route, but many families are less daunted by fast traffic.
An ocean side alternate might exist using the Old Kings Highway, which may be less hilly but mostly unpaved. An exploratory trip is in order. Some good friends tried a similar route with mixed results.
Truro hostel and all was good in the world again. The hostel is an old life saving station, precursor to the Coast Guard where men were stationed to rescue shipwrecked crew and passengers. It is at the end of North Pamet Road, within sight of the beach. And a nice beach it is.
hostel, like most, is no frills and comfortable with a large sitting room and spacious dinning room/kitchen, with plenty of fridge space and cooking implements. We brought all of our food, but next time we would buy all of the heavy stuff, if not everything, at the upscale market at the corner of South Pamet and Truro Center Road (the premium is more than offset by not carrying as much).
The hostel is maybe 100 yards from the beach, and they have all of the beach stuff you could want, chairs, towels, blankets, umbrellas, buckets, shovels, etc. We would leave all that home next time too. The beach is a wonderful place to walk (in fact I walked my son out their both nights to lull him to sleep in the unfamiliar place). Along the beach I could easily imagine walking all the way back to P'Town. In addition to the beach, there are numerous inland trails, just on the other side of the dunes. These are mostly woodland, but often wind up to the top of grassy dunes (read small hills) with great views of the ocean, and sometimes back to the bay. I hear these trails parallel the beach much of the length of the cape.
friend's trip a couple years ago.