First, only a few programs are limited to foriegn students (Stanford, Duke, and a few others). Second, they are not easy to get into, but not terribly difficult either. Most LLM programs serve as cash cows for the school, they are not ABA regulated, and the people in the programs don't figure into ABA reported numbers. Last, what school depends on what you want to specialize in. Yale is the obvious choice for people who want to be professors.