Cute, Romantic, and FAST
Beacon Hill Bistro has pretty brisk service, especially if you mention you've got a deadline; it's a good, classic French bistro in a nice small hotel setting, with a good, teensy bar.
Scollay Square's food isn't the greatest, but it's a handsome space and is usually empty enough in the dining room to avoid waits.
Silvertone is quite casual, but the food is a very good value (plus they have nice-priced wines and good drinks). It also moves pretty quickly, but it's a popular spot, especially before Orpheum shows (45 minute waits for tables not uncommon).
If you want to splurge, consider dining in the Cafe at No. 9 Park (no-reservations seating in the bar area); it's not too bad if you stick to the cafe menu (entrees under $25), and the cocktails are nonpareil.