Blue Sky in York Beach, a standout (and something of an oddity--in a good way--in York Beach). Breakfast at Norma's. Otherwise, we have always tried to stick with Maine seafood, simply prepared, as we have not been wowed by the places we've tried in York Beach. (But would love to hear if others are, for the next time we're in the area.) We stayed and ate at the Union Bluff, found the food mediocre.
In York, we love the dining room at Stonewall Kitchen, where we've eaten several lunches. The lobster BLT is splurge-worthy, but, really, everything we've had was good. I think they serve breakfast; I would bet that is wonderful.
We stayed at a hotel on the end of Beach Street last year, I think it was in May. (Googles it) Ahh, it was called Union Bluff Hotel. There was a suprisingly good breakfast buffet at the place next door, in what doubles as their conference room. In the evening, a surprising number of locals showed up just to eat at the hotel restaurant. We only had drinks and aps but they were all good.