Hi Scott,
Last year at this time, I was in the same boat as you wondering about all of these things because PCOM isn't the best at disseminating this info (surprise, surprise).
For myself, I decided to do three "away" rotations and the rest here for this year. The reason being is that I did not want to give up my apartment, constantly have to pack at the end of a rotation, and I am not a big fan of dorm life/public bathrooms. However, there were three hospitals outside of the philly region that I wanted to check out, so those are my "away" rotations.
When deciding on where to go for your rotations, you should try to go to the hospitals that you might be interested in for your residency (even if it's not for the speciality that you want to do). For example, I am on a rotation now that I know I would never want to do, however, a spot opened up at a hospital that I would be interested in doing my residency at. So, needless to say, I took it.
As for deciding which hospitals/health systems you would be interested in doing your residency at, you should decide what residencies you might be leaning towards and then through the AOA webpage you can look up hospitals that offer that residency and read up on them. If you're interested in Allopathic residencies then I guess you would need to look at Freida for the same information, although I am not 100% sure on that.
If you have any more questions, don't hesitate to ask. However, keep in mind that this is my 2 cents and someone else might see/do things differently
Take care,
abs
P.S. Don't forget to check out the blue rotation guide in the library. The information is relatively accurate.