I lived in Seal Cove for seven years. Its not a big island, six days is fine. So far you listed on the spots everyone else will be at. Head over to the Quiet Side to get away from the crowds who gather in Bar Harbor.
Cape Road will take you down to Seal Cove (part of Tremont) where there is a picnic area (boats in the harbor, opportunity to have a campfire down by the water, launch a kayak, see the sunset over the water).
Grab a lobster at Thurstons in Bernard across the harbor from Bass Harbor. The perfect spot to capture lobster boats in the harbor. Take a short hike on the Ship's Harbor Trail.
Explore Southwest Harbor. Boats in the harbor, little downtown that was used to film Stephen King's "Storm of the Century"
Drive along Sargent's Drive along Somes Sound and Northeast Harbor to see how the blue bloods and newly minted super rich live. Visit the Thuya Garden. See if you can sign up for a tour of Abby Rockefeller garden.
Get out on the water with a ranger guided trip to Baker's Island and see MDI from the water as well as lighthouses.
Keep in mind that if it is foggy, you might drive right past some beautiful scenery and not even know it.
If you set up to capture a sunrise on Cadillac, watch out for the bus loads of Chinese tourists that unload in front of you the second you are ready to snap the shot. Happened to a friend of mine.