I dont think there is a standard answer. I would try to stay away from large academic centers as much as I can for several reasons: easier grading, friendlier people, better hours in general. However, I would try to stick with an academic center if it shows on your dean's letter WHERE you actually did your rotation. I would also go with academic center if there is a big name person at the institution where you can get a letter from.
I actually had a chance to do some ambulatory Surgery at a rural site. It was great if you don't like surgery, but if you want to get some OR experience then you really need to be in a hospital, I did get a solid month of that.
Medicine, I'd say it's good to get a good mix of ambulatory and wards.
OB/Gyn- I worked with a community preceptor but we still ran over to the hospital for deliveries and GYN-surgeries on a regular basis. I'd say you'd probably be missing the bulk of real OB/Gyn if you tried to do a ward service.
Psych- A mix of outpatient and inpatient would probably be good. If you can see the inpatient schizophrenics and some of the outpatient mood disorders, that would be ideal. I would try to throw some child psych in there too. (So I just listed everything, you're probably going to have to sacrifice some or most of the above, so pick what interests you and read about the rest)
Peds- Again, a mix of ambulatory and inpatient would be best. You need to know how the ambulatory clinics work for the day to day stuff, but there are some sick kids that you need to know about too. (If you did get stuck in an ambulatory clinic, and you don't care about peds too much, just read about the crazy stuff in all that amazing free time you have... you'll probably be fine for the shelf)
Family- haven't done this yet, but I'd say this is fine to do ambulatory.