I agree with the previous posts. I ranked the schools according to research interests. At each school I was accepted to, I asked myself, "are there a lot of researchers doing stuff i'm interested in and who i would consider doing research rotations/thesis work for". Believe it or not, there were some schools where there weren't too many people in whose research I wasn't interested.
Ultimately, after MD/PhD training, you will mostly likely be applying to RESIDENCY programs so med school rankings in USNews is not a completely moot issue. Especially, if rankings are important to you consider not only the overall rank but also the "Residency Director's Rank." That will give you a rough indication as to how residency directors may potentially view you when you apply in 4+x years.