A.V.
I have not been to Stone Harbor but I used to go to Rehoboth when I was a kid. Dewey is not far from there and quieter. You could stay in Dewey and easily go to Rehoboth (or Ocean City) for bigger waves, boardwalk, etc. I haven't been in several years, but at least not long ago I'd consider it a family beach, moreso than Ocean City.
In renting homes like this, I'd take a look at the house, the location (it's a few blocks from the beach, but is it also a significantly nicer beach for the price?) and the things around it. We once rented a house in the Outer Banks where the water was so full of oysters the kids wouldn't swim in it. Try to find reviews of each house, too, and/or the rental company. They'll tell you if the place is well or poorly maintained, if the rental company is responsive, etc. Long and Foster in Deep Creek, MD always served us well so we went back to them several times.