Sounds like fun - good luck, Annie! I think those large races are on a whole different level - crazy, chaotic, but fun! The very first 5k I ever ran was the Race for the Cure in DC with over 30,000 runners. My SIL is a big runner and pulled me way to the front (where I really didn't need to be). Al Gore was VP then and he and Tipper were up front with their bodyguards (I don't think they needed to be up their either,lol)
Enjoy the race!!