I was in Maine a couple of years ago, but not for long. I had been spending quite a bit of time in Vermont, looking for a house, and decided at the last minute to take a quick peek at Maine.
Didn't have time to see much. Poked around in a few antique stores and drove along the coastline (which wasn't really visible -- obscured by trees, houses, and distance.)
I did stumble across the Portland Lighthouse and spent an enjoyable afternoon there. I found a nice comfortable rock at the base of the cliff and basked in the sun for several hours as the waves crashed around me and the seagulls eyed me with curiosity.