...no matter how you stack it. It would make sense for Utah, however. Being in the Pac-10 would give them a built in excuse for suffering through mediocre seasons in football. They could claim it's because they're in a tougher conference. The only thing they'll have to give up are the once in a century miracle season where they finish undefeated. That won't be happening again because they'll be in a tougher conference.
Based on how their fan base feels about things I think they'd prefere this. They'd be willing to give up the "even-a-blind-squirrel-finds-a-nut" season to have the built in excuse for being average the rest of the time.
As for TCU going to the Big 12, I haven't heard a single reason where this makes sense. They don't bring anything to the table that the Big 12 doesn't already have. At least with Utah going to the Pac-10, the Utes don't really bring anything either but the Pac-10 is desperate to have anyone and because of thier location they don't have any other options. They HAVE to get the Utes. Who else can they get? Silly Ute fans will say that they bring the SLC/Provo/Orem TV market but the irony is that they don't have that market. BYU has it in spades.