Well I don't know about the others, but as a student at Carleton college, I love the campus. It is in fact the reason I went to Carleton. The lakes in the middle of campus are very pretty; as are the trees in the fall.
Carnegie Mellon is a good school but the campus is pretty ugly, unfortunately. Can't say about the others, but I know CMU from being there a few summers ago.
The way your campus looks should be a small factor in wanting to go there. I don't step outside and admire how pretty everything is...I get in line at Starbucks and ride up the elevator in the library every morning to the top floor to study.
Pick the school where you'll get the best education. Although UC San Diego I think would be a good place to go to school/live.