Ross' network is so huge that I'm sure you'd have no problem finding dozens or even hundreds of useful contacts in the network in SoCal. UCLA's network may be bigger in SoCal, but if Ross' is a bit stronger but more cohesive and willing to help out, then you might find the Ross network to be even more useful to you later on in your career. I think you should listen to your gut and go with the community you feel more strongly about. I think you're absolutely right that it may be valuable to get out of SoCal for a while...a couple of Michigan winters may even lead you to appreciate Cali even more

And who knows, being away for a bit may even open your eyes to other new and exciting opportunities in fields you hadn't even previously considered, and the tight-knit Ross community will be there to support you all along the way.
then again, I might just be bitter that Anderson rejected me and Ross accepted me