I always recommend Lido Bottle Works in Newport. It's a dimly-light, intimate restaurant right on the docks but not over-the-top by any means, mainly because it's so small. Sit at the wine bar or covered patio tables, and you can go for a walk along the docks and hang by the firepits near Nobu…
Plenty of places with harbor views (Nobu, Zinque, Malibu Farms, Circle Hook, Lido Bottle Works, A&O Kitchen, Billys at the Beach, Louie’s at the bay) Less with ocean views (shake shack, beach comber)