SuitUp,
I think it is going to be a tough choice between UCLA (No $$) and USC (full ride), but it is a good problem to have in my opinion. This is how I would break it down.
UCLA scores over USC if you are looking for a post-MBA job and subsequent career outside Southern California/Greater LA region. Generally speaking, an MBA from UCLA has more prestige than USC's, period. On the contrary, USC's alumni network is as good as UCLA's when it comes to job prospects in LA area, if not better. In terms of culture, facilities, and other short-term parameters, there is not much difference based on my research. Also know that these things are subjective, but one's career goals are not and they always demand long-term perspective.
This is how it boils down, again, this is just my two cents. Scenario 1: If you are envisioning a career in LA and are eventually going to settle down in Southern California, I would close my eyes and go for USC, as 100K is 100K, no matter how you cut it. Scenario 2: If you are planning to settling down somewhere else in US, you need to buckle down and brainstorm what is more important to YOU.. a) dealing with $100K or b) better career opportunities, better recognition/pedigree of UCLA over USC outside the realm of Southern California.
Hope this helps. By the way, I have been waitlisted at UCLA and admitted to USC, so I tried my best to be as unbiased as possible, but I hope honest feedback always comes around.
Long story short, talk to as many people as you can and leave no stone unturned if you are stuck with Scenario 2.
Good luck.