We stayed at the Bar Harbor campground, last September.. It was only a few miles outside of the city.. Very nice, clean and reasonably priced.. They had a shuttle bus that would take you into the city if you liked.. Take the bus tour up to Cadillac mountain. The tour guide/bus drivers are a Hoot!!!
Just check the prices if you decide to stop in town for lunch.. I went into one bar (don't remember the name) that sold tickets for the tour bus and ordered a JW Black on the rocks while waiting for my wife to finish her shopping tour and it cost me $17.00!!!
Needless to say, we didn't have lunch there and found some good food at more reasonable prices nearby..
Safe and happy travels..