I spend a lot of time on mount desert island, where Bar Harbor is the "big city" so while I don't know anything about the specific excursions offered, I would say:
-Acadia is an amazing national park, if you do one thing on the island it should be to see Acadia
-There are (seasonally) free shuttles from the towns to the park, if you are an active/hiking type, just take the shuttle to one of the (many) mountains. Probably I'd recommend hiking Penobscot or Sargent and ending up at Jordan Pond house for lunch or tea. If a bus is more your speed, anything that does Park Loop Road / Thunder Hole is fine.
-(Jordan Pond house is an amazing location, but a couple years ago the gov't outsourced the food from the locals who had run it forever, and the quality of the foot - now run by a megacorp- has gone waaay down while the cost has continued to go up. So, honestly, the food will be overpriced, but you cannot beat the view if you sit outside. Sitting inside is...fine? But you'll get a better lobster roll almost literally anywhere else on the island)
-If they go out to Cranberry /Isleford, that is always fun.
-Cadillac Mountain is "the first place the sun touches in the morning" (....check locals facts and they'll know you come from away). It's beautiful at sunrise, but can be crowded mid-day
-Somes Sound is "the only natural fjord outside of Norway" (...I'm told) and one of the most beautiful places in the world. If there's any boat trips up and down the sound, that is always great.
-I'm sure they have some sort of "join a lobster man and see how it works" and probably that would be cool.
-I just re-read that you are interested in hiking. There's a ton of great and beautiful hiking in Acadia. You don't need an excursion, the maps are pretty clear if you are experienced. Cell service can be spotty on parts of hikes, but I've never done a hike that was out of range the entire time. Jordan Cliffs is awesome, but there are nesting falcons, so sometimes it's off limits (and there are iron rungs on this one, it's ... steep).
The shuttle is the Island Explorer:
http://www.exploreacadia.com/index.htm