special occasion dinner near Stonington
While it may be a tad over a half hour away from Stonington, I highly recommend Pip's at the Copper Beech Inn in Ivoryton. Also, right in Stonington Borough is Noah's which is more casual but consistently serves excellent food.
Copper Beech Inn
46 Main Street, Ivoryton, CT 06442
Would recommend Stonecroft Inn in nearby Ledyard. Very good food and a truly lovely and charming Inn. Another great place is Bea & Thistle Inn in Old Lyme. They offer seating in several dining rooms and the ambience is lovely with working fireplaces in several rooms. Food, wines, and service are also great. Think either one would fit your needs.