Here are the Pac-12 Bowls in order:
Rose - Stanford (assumes win over USC)
Alamo - First choice, but must select either the team (remaining) with the best conference record or teams within one game of that school
Holiday - Same stipulations as above... had USC last year so may not be interested but with Oregon off the table (likely Alamo-bound) they can choose between WSU, Utah, USC or UCLA
Foster Farms - Same stipulations as above, same options as at the end of the above list... If Holiday prefers WSU then they choose between Utah and USC (I know who I would take...)
Sun - No stipulations, can take any school they prefer... Best teams available at this point are Utah and UCLA
Las Vegas - Same as Sun
Cactus - Same as Sun/LV

Even if what I have read is true about WSU>Utah (which I doubt seriously), I imagine that the Sun Bowl would invite Utah over UCLA or Cal so the only way to get a BYU-Utah matchup would be to reject the invitation to seek out BYU in Vegas and, while that is what I want as a fan, I am not sure they would do that having been there just last year.

So, for BYU this leaves LV with the option of taking a lesser Pac-12 school than UCLA (Cal? Arizona? Can they even take these schools since they don't have a .500+ conference record?) to keep BYU or to take UCLA and let BYU go to Hawaii (which is what Hawaii wants in order to leave the door open for Univ of Hawaii to be in their bowl game next year) to avoid a bowl game that is a rematch of game already played.

It is a convoluted mess that won't get any clearer until we know the outcome of the Pac-12 championship.