Navigating Acadia is incredibly easy, as there's one main road -- the Park Loop Road -- that loops the park. There's one spur off this route that leads to the top of Cadillac Mountain, and an inner route that leads to Otter Cliff and the Fabrri Picnic Area.
An option to taking your own rig is to take advantage of the Island Explorer, a fleet of propane-powered shuttle buses that operate from late-June to early October. The shuttles stop at many of the scenic spots along the Park Loop Road, campgrounds, and trailheads.
Of course, you also can explore the park by bicycle by heading down the network of carriage paths that wend through the forests of Mount Desert Island. On our last trip to Acadia my wife and I pedaled all the way from Bar Harbor to Northeast Harbor, where we stopped for lunch and some shopping, and on back to Bar Harbor. These paths are perfect for youngsters, as you'll encounter no vehicle traffic.