Hmmm....Are you sure about needing the city tour?
Agree with your choice of Acadia Tour with the National Park service which we've done also in the morning their first tour of the day.
Our park ranger guide showed us many locations as we headed out and talked about the history of Bar Harbor. You will also be given a discount coupon (we were) for Testa's restaurant where we had a wonderful lunch after the tour then walked throughout the small Bar Harbor town area. That alone was easy to do no tour of the city really needed....JMHO of course.
Sorry for mentioning this to you about needing a city tour but just wanted to offer a suggestion. But you enjoy whatever you think works best for you.