Bizen has great Japanese, Baba Louis was already mentioned but I’ll second it, both Bizalions and Rubis offer a European cafe vibe ( great sandwiches/imported cheeses/order at counter type thing). Bistro box is also great, although be prepared to stand in line for 30+ minutes and then another 15 or so to get your food.

Edit: while not lunch, Naumkeag is doing their annual pumpkin show and it’s a nice fall activity if your looking for that sort of thing. You’ll need to buy tickets ahead of time though.