I like to serve champagne before dinner. Seems more celebratory and I also appreciate the taste before eating or drinking other things. Caviar, raw oysters, can be nice if you want to serve some food, but I think it's nice on its own. If you have several people drinking, I would serve everyone a glass of champagne before sitting down for dinner and plan for another bottle of something heavier to be served with dinner as people finish their champagne. Believe me, if you have four people, the bottle won't last long. If there will only be two of you, I would also invest in a champagne stopper that allows you to recork the bottle after it's opened so that you don't lose those wonderful bubbles. (And it's very festive to serve it in champagne flutes.)