Hello Songbird, and welcome to Pash!
Your ideas for the midnight lunch are wonderful -- I'm assuming that's your regional term for an after-party post-reception, correct? Just let me know if I'm on the right track with identifying this party, and I'll be happy to help with catering advice and other touches for the celebration.
For right now, I'd suggest that you add a little bit of novelty to your menu selections, such as ciabatta bread instead of the usual rye, unique recipes for salads -- anything to make your menu items things that your guests don't get everyday. A great caterer or personal chef can help you dream up twists to each item on your menu, and provide you with detailed expertise on how much food to get for your 200 person guest list.
For starters, let's just make sure I've classified your party correctly, and then we'll get into the fun stuff
Thanks for writing, and for the honor of allowing me to help out in any small way with the wedding plans~
Sharon Naylor