Have read through all the Mexican restaurant recs and now can't wait to try out a lot of them but wondered which you'd go to for a birthday dinner on the Saturday after T'giving for good food, lively atmosphere (and takes reservations)? Group of 5: 2 teens, 3 adults. Birthday boy likes his food way beyond spicy. Not so with the others. Boston/Cambridge/Somerville/Waltham environs would be easiest. Thanks!