Doing an away anywhere will help you a lot if you do a good job. As far as places not to go, that is all in the eye of the beholder. My advice to you would be to not use other people's experiences when trying to gauge a program/decide where to rotate. As I'm sure you can figure out, one person will absolutely love one place while another student who is there at the exact same time will want to gouge his eyes out every minute of every day. Just pick locations/programs you think you want to be at and do rotations there.