We were just in Kennebunkport over 4th of July. It's so cute. Get a lobster roll from the Clam Shack. Personally, I wasn't a fan of Alisson's, which is generally popular. In Kennebunk, the Kennebunk Inn has delicious lobster pot pie. The general store HB Provisions had the BEST corned beef hash I've ever had for breakfast. I heard Mabel's Lobster Claw restaurant is very good, but we didn't have a chance to make it there.
We stayed at Elizabeth Rose house in Kennebunk. The owners were very sweet. Good breakfast.
We did a whale watching tour. Make sure you triple up on sunscreen if you do. I ended up burnt so bad we had to cut our visit short, and that was WITH reapplying every 3 hours.