For my two year, my wife and I went to Charlie Trotter's which was spectacular. Unfortunately, I don't rate his cooking at the same level anywmore. Great, but I would rather have a meal at Avenues or Alinea.
I've also celebrated anniversaries at Everest. That is a great choice if you like your food with more definite French influences.
Ambria doesn't do much for me. I just wasn't that impressed by anything there.
The two best meals I have had recently were at Alinea or Avenues. Avenues is a great anniversary choice because you can walk around the North Michigan Ave. area before or after the meal. Of course, if you really want to splurge, have dinner there, get a room, and then send your wife to the Pennisula spa the next day.