What about the Blue Water Grill (probably too late) or the Strip House-good steak place on University Place (just south of Union Sq.)?

le impero in Tudor City 42nd bt 1st and 2nd - great italian - lovely setting....i like the gramercy tavern suggestion above also

I took my parents to Becco in the theater district for my dad's birthday and they love it there. It's casual but nice, and they may have reservations around 8pm after the pre-theater crowd leaves. It's northern Italian food, so there is pasta as well as all kinds of meat, chicken & fish dishes. They are seem to do a good job dealing with good sized groups as well.