Glad you had a great time Paul!  I know what you mean about old favorites...when you find something you like, you get in kind of a rut. 

If you're going to do a show next time and happen to be by North Avenue, I'd HIGHLY recommend Trattoria DiNotto.  My friend Karen and I have been going there for YEARS (ever since graduating college), and Joel and I hit that spot a couple weekends ago.  The food is incredible, service is unobtrusive and efficient, great atmosphere.  They tend to ask if you're going to a show, and will point you towards quicker-cooking dishes that will get you out in time for the show if time is an issue.

Also, here's a guide to restaurants by theatre.  You just click on the theatre you'll be visiting and it tells you the restaurants that are right by there. 

http://www.theatreinchicago.com/eat.php

If you're on north Halsted Street, I'd HIGHLY recommend Cafe Ba-Ba-Ree-Ba!  It's a Spanish restaurant (think tapas, paella, sangria).  Really a fun place!

As always, reservations are advised on those busy theatre nights, though some restaurants either don't take reservations, or take them only for large parties.