We like the Good Table in Cape Elizabeth. It's family run with Lisa (the chef) cooking utterly delicious food without the need to rip you off as if you were having dinner in midtown Manhattan as some Portland restaurants do.
We also like the mussels and Clam Chowder at Gilberts in the Old Port. For breakfast, we like sitting at the counter (the original one as you walk in) at Becky's. The grilled blueberry muffins are incredible. Their omelettes are fantastic because they don't add crap that makes omelettes "fluffy". They are simply eggs and the ingredients you want inside.