I've camped around Bar Harbor and north for years. I always camped at Blackwoods. If you don't need any hookups, it's a great spot. There is a path over to the ocean, where you can sit and enjoy the rocky coast. I camped at Schoodic Woods last year. It is very nicely laid out, lots of elbow room. Hard for me as my camper is not self contained, and they don't have showers. If you stay near Bar Harbor, don't just drive the park, get out and do some of the hiking trails along the carriage paths. Well worth it. Many good restaurants, don't miss some of the lobster pounds over in Southwest Harbor. Also, Head of the Harbor, if it's still there.
I also head further north. Sunset Point Campground in Harrington is a nice spot, with hookups. My favorite campground is up at Cobscook Bay State Park. No hookups, but beautiful campsites, the one I take is completely private, on the water. Bliss. Very quiet up past Ellsworth. I like it up there so much, I'm finally buying a place.