I've been to Au Bourguignon du Marais in the 4th twice now. It's a straight up bistro, simple French dishes, with a burgundian slant and a good wine list. The outdoor seating is quite pleasant on a quiet seat and the kitchen and staff are serious enough to make for a very good lunch.
Some favourite dishes.. A blanched tomato and fresh goat cheese salad, the classic hangar steak with shallots, and a surprisingly robust penne with chorizo. They also feature andouillette and it looks good, but I'm just not quite brave enough. Last time we were there we had a fantastic chocolate tarte, way better than anything else like it in Paris. Creamy and eggy, rich with chocolate but not too dense. Yum.