Any recommendations for a good place for brunch before going to see Mama Mia or Wicked on a Sunday? And why do you like it? thanks!

We like Bryant Park Grill & Cafe in back of the NY Public Library. It serves an excellent prix fixe brunch/lunch for $26, including a drink.
It's about a 12-block walk to either theater.

Blue Ribbon Bakery (which isn't a bakery) and The Cupping Room.

Wonderful brunch buffet at Brasserie 8 1/2.

Very upscale and refined brunch buffet at Aquavit. Salmon more ways than you thought possible.

The first one will leave you so full you might fall asleep (I would). The second is more restrained.

Another vote for Bryant Park. Good food and service -- close to the theater district.

Another choice might be RedEye Grill.

For casual and pretty good food, there are lots of places on West 46th between 8th and 9th, such as Joe Allen (American food) and Orso (Italian)--ame owners.
On the other side of the street is Becco, one of my favorite pre-theatre restaurants.
On West 43rd is Le Madeleine, if you prefer French-ish. There is a courtyard for dining in good weather.

And at 315 W 48th is Luxia, an often overlooked place that has excellent food and service
www.luxianyc.com