If you haven't already visited
Acadia National Park on the Maine coast, I'll suggest it as one of our favorite hiking/biking areas. There's also plenty to see in downtown Bar Harbor (very dog-friendly) and some good restaurants.
We've stayed in campgrounds in/near the park, but have decided to stay at
Schoodic Woods Campground the next time we visit. Your July time frame will probably rule this campground out, though. The B-Loop offers electricity and water, but no sewer service except the dump stations. From Schoodic, it's a ~1hr drive to Acadia, but you can also take the bus from the campground to the town of Winter Harbor and then catch the ferry to downtown Bar Harbor. From there, you can catch the
Island Explorer buses to various points in Acadia NP. Very bike friendly!
Typically, Schoodic campsites go quickly and I believe there is a 2-month booking window. That would mean that
now would be the time to book a site for the end of August or after Labor Day (our favorite time).