Here's my idea for an alignment for the Pac-12. It's a "zipper" format, similar to the one used by the ACC and Big Ten. It puts one L.A. team in each division, but keeps geographical rivalries intact. Each team would play 9 games - 5 division rivals, 2 annual interdivision rivalries, and 2 other interdivison games.

PACIFIC DIVISION*
Southern California
Stanford
Arizona State
Colorado
Oregon State
Washington State

WESTERN DIVISION*
UCLA
California
Arizona
Utah
Oregon
Washington

(*I'm not too attached to the division names. They're just the first that came to mind.)

Interdivision rivalries:
Southern California and Stanford vs. UCLA and California
Arizona State and Colorado vs. Arizona and Utah
Washington State and Oregon State vs. Washington and Oregon

So for example, in any given season, Utah would play:

California
UCLA
Arizona
Oregon
Washington
Arizona State
Colorado
Either USC or Stanford
Either Oregon State or Washington State

And, if this alignment isn't to your liking, a similar one with the same scheduling structure can be attained by simply swapping a few teams: swap USC or Stanford for California or UCLA, Arizona State or Colorado for Arizona or Utah, or Oregon State or Washington State for Oregon or Washington.