Greenville and Eustis areas are prime moose spotting areas. Eustis has an awesome amount of caches. Many are very family friendly. As far as the coast goes then most anywhere is good. You may want to visit Acadia National Park, or further up the coast for a more real Maine experience. As your trip gets closer you should check back for some more specific recommendations on caches. Bangor has a transportation museum that kids may like and depending on their ages there are children's museums in both Bangor and Portland. Up in Patton there is a lumbering museum that is very interesting as well. Hope this helps.