This response is from a current student.
"It is true that Keck is a commuter school. Despite this fact, we still have a very social / fun atmosphere, IMO. With all the social events planned in the first few weeks of school (beach day, bar nights, welcome dinner, team-building activities, etc.), you'll have plenty of chances to meet your fellow classmates.
There are numerous gatherings throughout the year (almost too many, in fact), including football games / tailgates, Halloween parties, and post-exam celebrations. Even if you don't live with your friends, you'll likely still see them for many hours on most days, studying in your MDL cubicles or at the library. Lastly, the students themselves are the biggest reason why Keck is a friendly place to be. The adcom prides itself on selecting sociable and genuine applicants. Throw in the fact that classes are P/NP for the first two years and you've got a good recipe for camaraderie. You also get a 2nd year student through the Big Sib program to hook you up if you are really clueless.
I almost forgot to mention that student orgs are another great way to interact with your peers. The basketball club meets weekly while the wilderness medicine club and surf club make several excursions during the year. With a relatively large student body and >65 active orgs, there's something for everyone at Keck.
Housing around campus isn't the best in terms of security & food options, but there is one complex right on the edge of HSC (City View Terrace) that hosts a sizable cohort of med students. There is also on-campus housing, but hardly any med students elect to live there. Most live in neighborhoods around 10-15 minutes away.
CONGRATS to all those accepted thus far; we look forward to seeing you at second look."