I think you mean Coast is closer to the west side of campus (yes, being from the east coast I still mess up east/west at times too). That being said, I'm really responding b/c Coast is definitely closer to Chem and at least some Bio and Physics. You're right that engineering is closer to Mesa. I don't know why engineering is completely across campus from Chem/Bio/Physics, but I have plenty of time to be annoyed by it when I walk between the two areas.
As for housing, I live in grad housing and like it. Sure I'd love to live somewhere move vibrant or w/ a dishwasher and washer/dryer, but grad housing lets me live off my stipend and not be broke. I use my car to get to museums/etc during the weekends, and I'm not much of a clubber (so maybe I am the boring La Jollan). Anyhow, if you're thinking its cheaper to live far off campus and commute, I will warn you that the parking permits were something like $800 per quarter! (Thankfully its free for grad housing other than single grad) I know a lot of people do bike/bus from other areas, and many of the single grads off campus have roommates.