My kid is a senior at Brown and choose Brown for this exact reason. He visited during an accepted students weekend and found the kids to be smart, “chill”, friendly and academically ambitious towards specific areas of interest. Every kid had a story of how the OC allowed them flexibility they took advantage of.
Four years later he absolutely believes it was the right decision for him. He has enjoyed the collaborative atmosphere, sense of community and mutual support from students and faculty.
He similarly was concerned about academic rigor but has realized flexibility doesn’t translate to easy. Actually to the contrary. Because he was able to choose the vast majority of his courses, he was extremely engaged and held himself to a very high standard. Of course not every kid approaches it that way but the OC allows you to dictate how broadly or deeply you want to pursue an interest.
Penn is an outstanding school and undoubtedly you could and or would thrive and be happy there. I have nothing bad to say or even a point of comparison. I can only share that my kid doesn’t regret in the least his decision to choose Brown having been confronted with the same decision.
Either way good luck and please ask if I can answer anything specific.