I, like citygirl. am an MS! at UCSF and while I love it here, I think the only advice I can give is to GO WHERE YOU FEEL MOST COMFORTABLE!
(I must warn you that I know nothing about Irvine, neither the school, nor the city, so I can't make a fair comparison vs UCSF, though I truly doubt that anyone can, despite their claims to the contrary. Read on if you are intrigued by this line of reasoning.)
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My question for you is what kind of an answer are you really expecting from people on this message board?
I'm always puzzled by the threads asking for advice on attending one school vs. another. (They become quite common around the May 15 deadline time as you might imagine.)
The bottom line is that unless a student has attended both schools (virtually never happens since med school transfers are essentially non-existent) or has close friends and/or relatives at both schools, no one will be able to provide a completely unbiased comparison for you.
We can all quote abstract notions like academic reputations, word of mouth, or clinical experiences, but in the end the decision should be made by where you feel like you would be happiest for the next 4+ years of your life and everything else will work itself out.
While some of my SoCal classmates find the weather in SF to be terrible (foggy and cold), I think it's heaven coming from the East Coast my whole life. The point is that choosing a school, much like most other major decisions in a person's life, comes down entirely to personal choice in which each person has a slightly different perspective and different priorities.
If living at home is very important to you, whether because you can't stand to be separated from your familty or you are really hellbent on saving money on rent, then so be it and go to UC Irvine. (I would personally hate to live at home during med school, but again that's just my opinion.) I just warn you to be wary of letting people on this board sway your decision too heavily.
If you have specific questions about UCSF, I would like to direct you to the Q& Advice about UCSF thread started by citygirl.
Good luck on your decision!
-NYC
P.S. Congrats for having 2 acceptances at such an early date if that is indeed the case!