As I've mentioned on these boards before, Maria Pia is my go-to Italian pre-theater spot. You may want to make a reservation as it can get crowded before shows. The food is good, the prices are right and I've never felt rushed.
319 West 51st Street, New York, NY 10019
With literally hundreds of restaurants to choose from in the Theater District,it would be helpful to know your cuisine preferences and a per person budget for food since opinions can differ as to what "not expensive" means. That said...
I am not a fan of Becco. The ayce pastas are mediocre, seating is sardine-tight, and the noise level is so hideously high that normal conversation impossible. Not exactly my idea of a comfortable, pleasant way to dine.
Trattoria Trecolor, on 47th St., b/t B;way & 8th Av., is our favorite Italian in that area. Well-prepared and tasty homestyle cuisine. Friendly, efficient service. Attractive decor and comfortably-spaced tables. Moderate prices.
West Bank Cafe, on 42nd St., b/t 9th & 10th Avs., serves excellent New American cuisine, service is friendly and capable, decor is pleasant, tables are nicely-spaced, and the noise level is conversation-friendly.
Marseille, on the corner of 9th Av. & 44th St., is a bustling French/Mediterranean brasserie with excellent food, good service, and eye-catching decor. They offer a 3-course dinner prix-fixe for $35.
Reservations are a must! I suggest 5:30 - 5:45 p.m., which will give you plenty of time for an unrushed, relaxing meal before strolling to your theater for an 8 p.m. curtain.
Enjoy the show and Bon Appetit!