We are getting married in Switzerland. Most of my FI's side speak English, but his parents do not!! I think that most of the public speaking will done by bilingual people so they speak in English and German. I also plan on throwing in other languages of the guests to highlight diversity. If anything seems to confusing, my FI can translate for everyone. I have been to a few weddings that were in German and not knowing the language allowed me enjoy the wedding in different ways and notice other things (like the ambiance, environment, sites, and smells).