There are quite a few good rotations here in cali, (i am only familiar with SoCal tho) however, don't you have to do rotations in your third year that are affiliated with your school/hospital? Are you talking about doing an elective? This is unusual as a third year. Even if you were to do a rotation somewhere else, most hospitals or medical schools will not take a third year, especially if they're from another school.
As a third year, we were only allowed to rotations affiliated with our school. We had our "block", which consisted of our core rotations and these had to be done at our affiliated hospitals. As a fourth year we were then allowed to do away rotations/electives at pretty much any institution. I am pretty sure this is the norm for most medical schools. Correct me if I am wrong.