Hola,
I’m a native Spanish speaker from Spain (I live in the U.S., spoke English all my life with a native English speaking father and my English could be better than my Spanish). Since I am Spanish, we use vosotros. While I heard people in the U.S. learn “ustedes comen”, I would say “vosotros coméis”.
Yep, it was in the textbook, but just like the Barthalona lisp, it was basically a bit of trivia we were never expected to actually learn.