what i'm learning is that for the most part, a rotation is what you make of it. some students put in extra work regardless of what the preceptor requires of you and get more out of it, or you can do the bare minimum.
at st anthony in chicago, you can complete all of your core rotations here, except psych, and many electives, and basically have a pretty good experience. i would have to say that ob/gyn is the best and most demanding and if its something you are considering i would definitely recommend it, because you will get more hands on experience than you could ever desire. you will be taking part of c-sections and vaginal deliveries day 1, and be pimped to no limit esp by certain docs and midwives, but you will realize when you begin studying for step 2, that ob/gyn will require the least amount of addtl studying b/c of the rotation itself.
hope this helps, if you have any more questions, let me know. later.