I think this is the big issue. People have already said 12-Pac fans don't travel all that well. We expect them to travel twice in one month to the same location? If you think the team is good enough to spend money to go see them in the CCG, you probably think they're good enough to risk waiting to see them in the BCS game, not the CCG.
In the end, I think we want a model where the CCG is an important game that is well-attended. If the smart people determine that there is a better chance of filling the Rose Bowl on a consistent basis (regardless of who is playing) than there would be if you rotated the game or chose a different permanent site, I guess I'm fine with the Rose Bowl.
One more reason to push for Vegas, IMO. I would rather see a smaller stadium packed than a half empty Rose Bowl, which we know would happen with some regularity. It's damn hard to get 100k people to show up for anything, especially if you're going to ask them to do it again in a month.