I won't be a lot of help because I went to Maine for a conference, not really a vacation, but I did add an extra day and had some free time to explore. I can tell you that I LOVED it there! I've been learning that I really like the smaller towns more than the big cities.
I stayed in Portland at the Eastland Park Hotel, which was within walking distance of the harbor and a few shops and restaurants. I loved the small boutique-type shops there, and I ate some pretty good food too!
I spent one of my extra days driving up to Freeport to shop, and that was REALLY great! I liked it because it wasn't like being in a big mall. The main street was just lined with small buildings with shops in them, both boutique shops, as well as the big-name stuff (GAP, Bath & Body, etc.).
I spent another extra day driving down to Kittery, near the New Hampshire border. It was okay, but I much preferred Freeport. I actually got bored, I'm not sure if it was the locale, or because I had been shopping at Freeport the day before. I left early, and I actually really enjoyed the rest of my day driving around along the coast. I stopped at a lighthouse where I took some pictures and had lunch at a little place there, then I drove back up to Portland. I stopped along the way a couple of times to take pictures of the shoreline.
I also drove through Kennebunk, but didn't stop (it was raining, and very crowded because it was Discoverer's day weekend). I wished I had spent time there though, it looked like some place I would've liked to walk around. I also wished I went up to Acadia. I was planning too, then I thought maybe it was too far, esp. because I was alone, but looking back, I think I could've done it.
If I had the chance, I would definitely return!