Is the UVA program you are referring to the Young Writers Workshop? I did that program in high school and there is a really strong alumni network still–it is a fantastic program, but I thought it was on hiatus for 2023? I think it is coming back in 2024, however.
I know several people who have taught at the Sewanee program and it seems like it would be a great experience, as well. I’ve heard nothing but good things about it and the location is magical. Sewanee has an adult writing conference each summer that is very highly regarded and competitive to attend and the high school program attracts really amazing guest artists and faculty via that close connection.