For something fun and a little less formal, there is a French/Cambodian bistro called Elephant Walk (with a sister restaurant named Carambola in Waltham). Cambodian-influenced French, and French-influenced Cambodian. Don't know how it works on the vegetarian side, but I'd bet pretty well. Locations in Brookline/Cambridge. In Newton, which is a quick pop out on the Turnpike, there is Ariadne in Newtonville, and Lumiere in West Newton. You can do as well in Boston if you know where, but the lower cost may justify cab fare.