This question suggests you don't fully appreciate just how small of a town Bangor is so you might want to do a bit of research on what you're going to do there before you go. That said, Bangor is very small and doesn't have a "walking" downtown (not even in the way that larger car-oriented American cities still do), so you wouldn't really miss anything staying at the airport if you wanted the Starwood nights. You would need a car for any trip to Bangor anyway, and it's not like the airport is far out of town or anything.

But, most tourists to the region would likely be focusing on Acadia National Park and the coast more so than Bangor itself, and while you could plausibly stay here during an Acadia-focused trip, it would certainly be more hassle than staying somewhere on the coast.