Had a similar situation to you last summer. Tons of great recommendations on here and everyone has their favorites. When it all came down to it though we just went for it. It's hard to plan for how you might feel or what you may be in the mood for before or after a big travel day. We enjoyed just strolling down the streets and checking things out. One cool thing IMO is you don't necessarily need to commit to a big sit down one and done meal. My wife and I just stopped at one place for a smallish lobster roll, then kept strolling for a crab cake, although it wasn't where you'd expect. we were able to kinda eat and explore doing it that way. There are multiple ice cream and candy shops as well so you can see what is around when you are feeling like it's time for whatever you want to eat. There were waits at some of the popular places, but since we didn't have that much time we didn't wait around for those. There are plenty of places you can just pop in and grab a bite. (Disclaimer, Ive only been once as an adult, so maybe my experience was an anomaly). Also, a few streets of the Main Street we found some great antique shops with a cool Irish pub mixed in, food was good, crab cake was even better than the popular place on the main drag.