statcan

It seems like UNC has quite a few faculty working in clinical trials. You can find 14 of them listed under "clinical trials" here. It doesn't seem to me like Wisconsin has a clearly bigger focus on this area than UNC.
There's also the "IMPACT" program joint with UNC, NC State and Duke with plenty of UNC Biostatistics faculty taking part: http://www2.cscc.unc.edu/impact7/ . To add to this, the primary grant funding this project is focused on cancer clinical trials, entitled "Statistical Methods for Cancer Clinical Trials". 
I don't know too much about this field but from a first glance, it seems to me like UNC is a great place for your interests. What makes you say that Wisconsin has better opportunities? 

The CMU visit day is not until this weekend. If people reject their offers, they'll most likely do so starting next week.

This seems to be the thinking from many people, and while it may be true in some programs, it's not true in the others. For example, I attend a top-5 biostats program (not UW), and our coursework covers measure theory, limit theory, decision theory, etc. just like a traditional statistics program would.
I don't think you can put all biostatistics programs in a vacuum and simply say "well it's biostatistics so it's less theoretical." The same goes for statistics--some even top tier programs (e.g., NCSU), will be more applied than the more theoretical biostatistics programs. We're not talking about statistics vs biostatistics here, we're talking about UW Biostatistics vs. CMU Statistics. 
 

Something that I don't hear talked about much here is the environment of the two types of departments. At UW, you'll be in a school of public health, and most of your fellow students will care about making an impact to genetics/public health in addition to statistics and professors will be very involved in large biomedical research collaborations. At CMU, more students will care about math, computer science, and a wider range of research - a much more liberal arts environment.