We often travel from Danville, VT, Best route wold be to RT 2 East from St. J, through scenic White Mts all the way to Newport ME, pick up the Maine Tpk east almost to Bangor, and follow signs SE to Bar Harbor. Much of the road has been upgraded and it is a smooth ride all the way, The only serious hill is just east of Randolph NH, but it shouldn’t slow you down. Mount Desert Island had 4 Million Visitors last year, so if you are going in the Summer you’d best reserve a spot NOW! We always go in the Fall and stay on the “Quiet Side”, so never had a problem. Wish we were going with you!