Here's my response to Lori B, who was looking for fresh ideas for not-too-formal places in the Back Bay/South End:
Try Union Bar and Grill, a brand-spanking-new place on Washington Street near Union Park. Meets all your requirements (I've been three times this week, with very consistent and fine results), and is as yet unreviewed (though it has been written about).
Smart without being too fancy, warm-feeling and luxe without being too precious, and featuring excellent, very friendly service. Bartenders know their cocktails (many are ex-Limbo).
My only beef, and it's a small one: all-American wine list, in keeping with the rather American (though quite creative) cuisine. I'd rather see more global offerings: American wine on the East Coast often seems like a poor value to me, though I did find a fairly-priced Cali Syrah last night (McDowell, $28).
For Chowhounds on limited budgets (like me), the noteworthy dishes are on the appetizer menu, with most in the high single digits: spaghettini with rock crab, risotto with sweet corn, goat cheese & eggplant salad, maccheroni with fennel sausage, lobster fricassee with gnocchi. I was less wowed by the smoked bluefish app. Entrees aren't cheap, ranging in the high 20s/low 30s, but are not tiny. Very good desserts (e.g., a fine bread pudding).