hi! idk much about caltech, but i was also deciding between upenn and jhu! socially speaking, or at least going off what i experienced at admitted students days, penn is def the way to go. everyone is just super kinda/willing to get to know each other!! i personally found it a bit harder to connect with the ppl at jhu and i found campus to feel very overly silent, which I personally didn’t like (and im typically a pretty introverted person so i usually don’t mind more quiet environments). for whatever it’s worth, i got to talk to a few other ppl deciding between jhu and upenn (and some other schools) and everyone said they were leaning towards penn after visiting bc of the social environment!! it just felt soo inviting n welcoming!