My family is planning a 3/4 day trip to DC between xmas and new years. Any advice, info, tips etc... related to crowds and what to do? Already submitted requests for tours of White House, Supreme Court and Printing & Engraving thru our congress people. Would like to do Smithsonian, monuments, a little shopping for the ladies, fun dining. Traveling with two grown children ages 17 and 20. Thanks for any help.