I got in May 13th.
Full disclosure, I'm still hoping to get of WLs at both schools.
I'd say UM because you potentially want to go back to Cali. Seems like UM might have more reach out there.
That said, I loved NU when I visited, and liked the students more there than at UM (they seemed more mature at NU, and I'm a couple of years out of school). This is obviously anecdotal evidence, though.
I don't know what the living situation is a NU, but 1Ls at UM seem to love living in the quad - seems like figuring out the living situation at UM would be less stressful.
That said, I don't think you can go wrong.