For foreign students, a lot of times the best place to go for electives is any place that will accept you!
It's not easy to find one even after you apply to fifty different places, so if you get accepted, then go for sure!
How do you pick where to go? Like MedGrunt said, you can use that list from the link above of schools that will accept foreign students, or you can do what I did, which is google the list of US Top Hospitals, and then start applying to all of those. There are a lot more schools out there that will actually accept foreign students, though keep in mind that a research elective is easier to get than a clinical electives, esp at the bigger hospitals.
You're right, surgery is a very difficult field to get into in the US, so if you have one elective done, you'll be increasing your chances over other foreign medical students, but I don't think you'll boost them significantly to really get ahead of the American graduates. You may want to pick a different field, or if you really want to go into surgery, then try to do some more research work in the US after you graduate and push for some clinic time once you have that set up. A very high step 1 and 2 score could also be very helpful... as always.
Since you're in the end of your fourth year, start applying to schools, fast.