Acadia is all about bicycling and hiking - and driving up to the top of Cadillac Mountain to see the sunrise (first spot on the continental USA to get hit by sun in the morning). Definitely can spend a week there (that is what we've done with older teenagers who are outdoorsy) if that is what you want to do, but... are your girls going to want to do that for 5 days? You might want to think like 3 days - one day for hiking, one day for bicycling and Jordan Pond House for lunch, one day for Cadillac Mountain sunrise and a couple other spots.
In Connecticut, if you can, check out Gillette Castle. Mystic Seaport is good. I wouldn't make an effort to see Mystic Aquarium - it has been years since I've been there, but I thought it was pretty ho-hum.
