Acadia is a park without any lodging within its borders. As a result, you'll have to look in the small towns -- Bar Harbor, Seal Harbor, Northeast Harbor, Southwest Harbor, Hulls Cove, and Bass Harbor -- that fringe the park.
Bar Harbor, located on the northeast corner of Mount Desert Island right next to the park, is the most prominent "gateway" to Acadia and has a great number of options when it comes to accommodations.
The question is, what sort of accommodation do you want? There are name-brand hotels and motels in the area, as well as a great number of charming bed-and-breakfast establishments (some within walking distance of the park) that will send you off for the day well-fed, as well as some water-view cottages for rent.
You even can rent entire homes for your stay, a move that could actually end up saving you money as you won't have to eat out all the time.
Looking for a cottage rental? This can be great for the family, although make sure you get sound descriptions concerning the size of the rental. We've stayed in some that well-define "cozy." The nice thing about these, in addition to the water views to be had, are that you can rent them by either the day or the week.
If you look into a cottage rental, keep in mind the location of the main road, Route 3, to the property. You don't want to be kept up by traffic.
Some of the grand hotels in downtown Bar Harbor also offer water views, of Frenchman Bay, and also provide walking access to the downtown area with its great shops and restaurants.
For other properties in the Bar Harbor area, check out the chamber of commerce's lodging directory.
Beyond Bar Harbor, the Claremont Hotel in Southwest Harbor long has a tradition of catering to Mount Desert Island visitors. Located near the mouth of Somes Sound, the Claremont first opened its doors in 1884 and has been greeting friends and families ever since. Along with offering hotel rooms, the Claremount has guest cottages, some of which can sleep seven.