Tough call, but I'd go Texas/LSU. More hype around this one than last year's Texas/Georgia since not many gave Texas a chance. It'll be Big 12 vs SEC for real now that we've bloodied their nose. The ou game is awesome, but one of many to come and go.
The LSU crowd will be LOUD! The Texas crowd will be LOUD! DKR will be rocking off the ground!!! We will be the underdogs again and a win here will be unforgettable.
OTOH, next year, LSU/Texas may even be bigger. Kick'em in the teeth twice and they'll have tears in their eyes.
Hope that helps. Or...you could get your wife to fill in for you and go to both?