If I were choosing what to do and hadn't been in Ames before, here's what I would do assuming you're staying at Hilton Garden Inn in West Ames:
Wed night: Perfect Games is right next door. They have bowling, arcade games and a sports bar. Plenty to do for the family.
Thursday: I would probably hit up Olde Main...that is UNLESS The Cafe is open on Thanksgiving. Search Google for The Cafe and if it's open, don't miss it. After lunch, I would walk through campus. The students will be gone, so you should be able to park in any lot you want and walk around.
Thursday night: watch some football at either Wallaby's or BWW.
Friday: Do Hickory Park for lunch. It's going to be late by the time the game is over, so I don't know that you'll want to go there at 9:30 or even if they'll be open.
Friday afternoon: If you like to tailgate, grab some beer at HyVee or Cyclone Liquor on S. 4th and head to the stadium. It's going to cost you $20 to park, but it's nice to have a home base vs being a nomad. If you really don't want to tailgate that much and want to show up right before game time, I would suggest either the KMart lot shuttle or parking at the HyVee and walking (probably a mile).
Friday night: After the game, find a place that will deliver pizza to your room (Pizza Pit or Jeff's Pizza) OR, go to West Towne Pub right down from your hotel.
I personally don't get the people saying "go to Des Moines". There's plenty to do in Ames, even over a holiday weekend.