Well, you're going to want to rank your current acceptances and do it quickly. Base your decision on the most important factors to you - rank, financials, location, program, etc. Weight these all and then assign a final score to each school. Then, when you've decided your school, send the deposit in. You may have to eat that cost, but it's better than counting on waitlists coming through and being screwed. Applications are up 30% this year, and deans of admission can get fired for overenrolling by as few as 25 students so waitlists are gonna be really up in the air this year. Reserve your spot at your top choice and then, if you get into Wash U or any of the others, you'll have good choices to make.
To be honest with you I would just send the money in to whichever school is ranked the highest. In this economy you need to make yourself as attractive as possible as a potential employee, and the best way to do that is to go to the best school possible.