ychennay I don't think it's super critical to visit. I live in SoCal, so as an undergrad I have either attended or visited Stanford, UCLA, USC, and UCI. I agree that their "vibes" are pretty well-reflected in their admissions events and media and by their representatives (alums, current students, etc).
UCLA is on the "west side" while USC is "downtown", which will change where you live, but where you hang out on the weekends (beaches, restaurants, clubs, hiking trails) will be the same.
UCI is in Orange County, which is a much more suburban environment, but has access to different hiking trails and to OC beaches. Merage is also only about ~100 students, with almost 40% international, so that's something to consider if you planned on connecting with many other students who will stay in the region. And I can't speak to Haas.
For me, the biggest factors were social/network fit (which as I said in my experience is pretty well-captured in their admissions), research programs, and $$$. The actual geographic layout of campus didn't matter to me because they're all very similar: state-of the art lecture halls, meeting rooms, and computer labs, all in great weather.
It's only a 2-year commitment (not even! it's really only 18 months on-campus, with a summer internship). If you realize you don't like the feng shui of the quad, then it'll be over soon anyay. I plan to be so buried in Excel spreadsheets that I won't even notice the campus. Not to mention treks, travel programs, and study groups. The experience is what you make it.
Attitude is more important than setting, and you seem to have an easygoing attitude. Do what you want and don't worry about other people's preconceived notions about having to visit first. If it's causing you stress to visit, then don't do it!