I'm going with Ariz -2.5, but see this as a close game that could go either way. Ariz should be a touch more motivated after losing the championship game on the road two years in a row (as stated above). Home arena should be just enough to put them over the top.
SJ's offense with QB-Grieb is bit better than Arizona's, but Bonner has been red hot lately and SJ's defense hasn't been that great. That Ariz defense is something else. I believe they held SJ to less than 10 second half points in their last meeting at SJ. They held the excellent LA offense to 42 points and held LA to 3-8 on 3rd down.