Let's just clear a few things up about rotations. Your 3rd year you CANNOT go wherever you want. You will be assigned, via lottery system, to a region (Iowa, Michigan, Ohio, St. Louis). Within your region, you will have a lottery for a specific city/hospital. If you stay in Des Moines, you will rotate at various hospitals in the area. Otherwise, you will be stationed at a single hospital (few exceptions) within a city in the region you were assigned via lottery. 99% of people get their first two picks for region (Iowa, Ohio, Michigan, etc...).
Fourth year, you can go anywhere you want as long as the Clinical Affairs office can approve the site. You are required to do 8 weeks of FM or community med, but this can be anywhere. The rest of fourth year is free for electives.