See my post on the first page for details.
If you want to stay in one place for four years, your best bet is to pick the Erie campus for 1st/2nd year and then try to get Millcreek or St. Vincent for your rotation site. Millcreek isn't popular, and I'd imagine if you want it, you're likely to get it, although there's no guarantees with rotation site selection. Meanwhile, the Allegheny site nearest to Seton Hill is very popular since it's in an urban area and a lot of students are from Pittsburgh, so I wouldn't put all your eggs in the basket of picking Seton Hill and then not having to move.