It is also important to understand that the rigor at a school can vary a great deal depending on the program. I think at Penn, some programs are extraordinarily rigorous. That is especially true in engineering and hard sciences.
The Comp. Science program is very challenging and the project requirements are extensive. I know a lot of people who attend top colleges and I have never seen this level of rigor before. One semester she was averaging 50-60 hours of homework per week. The students that hang in there know a lot. The program does not get a lot of attention in rankings but it does from employers. The last two summers the big tech companies she worked for were very surprised by the depth and breadth of her abilities.