If you have the flexibility to live where you want and are not tied to being within some mileage of a career, then Maine has quite a few very good options. Belfast would be at the top of my list but there are many terrific communities all along the mid-coast region. Come visit and see for yourself. Belfast has a nice balance between summer tourism, with the fairs and activities that tourists crave, but has a strong year-round community of individualists. If you are into localism, there are few better places in Maine.
If you are not used to the culture of rural Maine living (and most of Maine is rural living) I think it's important to be hooked into your community, whether through work, extra-curriculars, or family. My one real gripe has been a serious lack of cultural diversity. By that I mean we don't exactly get world class arts around here, although I don't even have time to go to what good stuff there is. Nor is Maine known for its ethnic diversity.
Don't plan on visiting the Daks too often: it's a loooong haul. But I've kept a pretty full outdoor life living halfway between Acadia and Baxter. Greater Bangor also has a lot of very good local trails for daily biking and skiing.
It takes a certain kind of person to want to live in Bar Harbor year-round. Much of the town shuts down in Fall for about eight months. You must either have enough money to build your own castle, complete with entertainment options (bowling alley anyone?), be happy living "alone" during battering storms, or have the ability to leave frequently. If you were serious about that kind of retirement, there better options than Bar Harbor on Mt. Desert Island.
I've lived in the greater Bangor region for about ten years. For what it's worth, I twice decided to stay when faced with career decisions. If I could do what I do now and live in the Belfast-Camden region, I would go in a second. For reference, my opinions are in comparison to central CT, central MA, and the Upper Valley of NH.
If you come up for a scouting mission, feel free to give a holler.