I am doing computational biology research, and while computational biologists definitely aren't in the majority in MSTP's, I don't think it's all that rare - there are several computational biology/bioinformatics oriented MSTP's in my program, and several of our interviewees this year were interested in computational work. Our school doesn't have a PhD program in computational biology, so I am doing the biophysics PhD program. The program is very flexible so I can take classes that will suit my needs - something to keep in mind, since going with a biological science PhD program may make some aspects easier (minor degree requirements, graduating in a reasonable amount of time, etc).