For people that you _might_ forget it should be pretty easy to summarize in a sentence or two. Two sentences should easily cover when, where, and why you met. Throw in common contacts and you're good to go. Obviously these same two sentences might not encapsulate why your wife is important to you, but, really, you aren't quite likely to forget that either.
Why do you say that? It seems like an important thing to keep track of, for people who you don't keep in regular contact with. Prevents "Who the heck is Greg Bobberton?", if you can just look and see "Greg Bobberton: that guy from the Widgetpalooza conference, was interested in that one idea I had" (obviously with less vague specifics).
