Hi there! I’m a 22-yr old CSU dropout > CCC > UC transfer (admitted this year to UCSC for Biology :D). I’m from Orange County. Though I can’t exactly comment on the inclusiveness of each UC and their particular strengths on welcoming incoming students, I can give you my insight into the “college experience” as an undergraduate.
I will say that in my 3-4 years of going through college with the combined stories of UC friends that the experience will be unique to the student no matter what. I know that when I first started undergrad that being social was ultimately up to me, as in I had to find the clubs/frats/programs that I believed will enrich my college experience, and they did though it was not my highest priority. The only way to do this is research the campus and what they offer. You mention that your child would like to attend UC as a transfer student, and what I know about Berkeley is that they have an amazing Greek Life. So if your student is enthusiastic about that then Cal would be a great option. I absolutely love the campus architecture and I have no doubt that your student should have all the inspiration they need to get involved once they feel the sense of prestige and achievement of their hard work upon transfer. It just takes some research on their part.
I was personally against the CC route back when I was admitted to CSU in hs, but as I finish my last term here I’ve made lots of friends and connections, even plenty of professors whom I can trust for a LOR to help find opportunities in transfer. Some of those friends are actually attending my university soon too, and this I’m grateful for because I don’t really have to worry about finding new friends once I transfer. As far as my social life in CC I just joined a STEM club and have a part-time job, so it was secondary for my mentality. Like I said, I’ve only been through these things because I APPLIED myself. They were all offered to me and all I had to do was say “I want to do this”. It is in the best interest of the student to take that extra step and apply themselves. Housing is usually guaranteed for transfers like it is for freshman, but not required.
One thing that I will mention is that my sense of having a social life and inclusiveness has somewhat degraded in my CC years because my mentality focused more on doing well in my classes. That’s not to say that I won’t participate in clubs or programs, I’m actually starting to look into research opportunities at the UC. I am very happy and grateful for where I am today.
Long story short, every UC has different qualities/opportunities that they can offer as far as welcoming students (e.g. Club Day, Transfer Day, Greek Life, etc.), but ultimately it’s based on how the student applies themselves in any uni they attend. Each student is unique to the university, and each university is unique to the student.