(1) LA is a huge media center. Riley will get a LOT more press being at USC in LA than he will (via ESPN and the SEC Network) by staying at Oklahoma in Norman. If he wants an accelerated path to a NFL job, then the exposure that he'll get by being in LA (vs. Norman) should be advantageous to him. Who knows what he hopes to get from the 'media advantage' ... probably some ambition beyond coaching college football.
(2) If Riley does well (and most people expect this to happen) in the PAC-12-is-easier-than-SEC, then he'll be in the CFP with regularity.
(3) LA is a great town IF IF IF you are stinking rich. (Not so much for middle class / upper middle class people any more.) Riley can take the private helicopter from his Beverly Hills home to the USC football facilities, so the un-Godly commute won't impact him or his family.
He could have pretty much any NFL opening he wanted this year. Kliff Kingsbury got a job after getting fired. The NFL types are desperate for offensive creativity. I think this was a move to get a reset on expectations and play in a league with less competition going forward.
Many Southern Cal folks would rather soak in some sun rather than go to a football game! I wouldn't say; it's a better job! The money will certainly be in the SEC when Oklahoma joins. Biggest thing: "it's not like Oklahoma is Washington State or Hawaii type job - they have National Titles and tradition!
On the surface; I agree! But, Oklahoma is a premium job as well! More premium than Southern Cal - maybe not 25 years ago! As the ghost of Trojans past teams still echoed. But, that has been a while now! They won it last in 2000 and have been a top 10 caliber team pretty much every year since. They can recruit kids from all over there and football means something there.
The future Oklahoma coach is going to get instant credibility due to the affiliation with the SEC(pukes). How long will they give him at Southern Cal?