Close by to Kennebunk, the Maine Diner is a good bet....in Wells Maine. Very Very popular, expect some waiting time to be seated. But there's a gift shop to hang out while waiting. Kenebunk is a little too upscale for me.
Ogunquit has a good Chinese place called "Yum Mee". (recommend Chicago style Chop Suey) Congdon's Donuts on the post road in Wells is worth a stop. The Lobster Pound in Ogunquit is very good.
Late fall early winter is not the best time of year for eats...many are closed for the season. In fact all of Perkin's Cove where some nice places with excellent views is closed.
If you go back during the warmer seasons...at York Beach my all time favorite is Goldenrod Kisses. It's like a trip back in time. Excellent Taffy, Ice Cream, and good old fashioned comfort food.
In York, Flo's hot dogs is sort of a landmark. Never ate there myself, but is legendary for the rude treatment by the server.
Bob's Clam Hut in Route One in Kittery is a real fun place.
Remember Coastal Maine roadfood has lots of competition for the tourist dollars. If your food ain't good, you don't survive.