Daughter's fiance' to ask for her hand in marriage. How did you respond?

My daughter and her boyfriend have been together just over 4 years now. They've been exclusive since their junior year at U of M. He spent 27 months in the Peace Corps, and they remained committed to each other through all of that. He returned to the U.S. in September, gathered his belongings and moved to Chicago with her. They're coming home for Thanksgiving and my wife and I believe he's going to talk to us about their future.

What are your experiences? Any words of wisdom?