First of all, I'm not sure if you're transferring or coming straight out of high school, but if it's the latter, I'd work on the GPA at a Community College and do a transfer.
Secondly, I have no idea why an aspiring planner would be turned off by a metropolis that is so diverse and complex in its planning issues on local, regional and even national scales. "The surrounding area," offers a plethora of examples on what works and what does not.
Thirdly, I am not sure what you mean by "Social Atmosphere." I grew up in the I.E. and have come across a small sense of disdain whenever I tell people where I'm from. Where does this prejudice come from? Maybe you watch too many shows like The O.C. which depict the I.E. as gang infested and dumb white people.
It's really short-sighted to generalize people just because they come from a geographical region. There are great people in the I.E. just as there are in SLO, in L.A. in the Bay Area. Riverside, CA happens to be one of the most innovative cities (in planning and sustainability) I've studied in all of Southern California, excluding major ones like LA and SD.
With that being said. There are so many awesome vibrant places that are somewhat dense, and close to campus that you can find a nice home at.
My friend lives in a rooftop suite in Downtown L.A. takes him 20 - 30 mins to get to class. Claremont Village is a bike ride away from campus...awesome place. Downtown Brea and Fullerton offer fun environments to live...you can take the train to Pomona station from Fullerton. I know some people who are commuting from Pasadena/Glendale area. about 30-40 mins at worst. I lived in Chino Hills for 7 months...that was a blast...20 mins from school.
There are Girls everywhere too. The odds are good for you man...especially in the college atmosphere of Fullerton. CSUF was recently rated in the top 5 for most beautiful girls at a college campus...my wife went there
Whatever school you go for, don't sell yourself short because of GPA or whatever...GO FOR IT!