I wouldn't recommend making a fuss over trying to get beef on weck. It truly is not anything to write home about.
I would recommend Buffalo pizza from Bocce Club or La Nova, and the cajun honey butter BBQ wings from Bar-Bill. You might want to order takeout from Bar-Bill unless you plan to be there in line for a table when the doors open.
Definitely go to the Falls if they've never been.
Don't plan anything for Sunday other than going to the game, and park in someone's yard away from the stadium lots so you can get out faster. I usually park about a mile away.
If you need something else to do on Saturday and want some memorabilia, try the BFLO Store, Dave & Adam's, and the Walden Galleria.