Others have mentioned this, but taking the train is a great way to make travel part of the fun. The train is much more comfortable than driving or flying, and if they've never rode one it'll be a cool experience. I saw you're sticking to the east coast which is great for train trips. If you're in the Northeast then the Vermonter is a beautiful ride that goes from DC to St. Albans, Vermont, right on the border with Canada, also making stops in Vermont's major cities and a bushel of other states. You've also got the Downeaster between Boston, MA and Brunswick, ME which is very pretty in the winter if you like the cold. If you're closer to the south then the Palmetto (starting in NYC) has service between DC, Raleigh NC, Charleston SC, Savannah GA, and Jacksonville, Orlando, and Miami FL (last stop). Finally the Northeast Regional will get you between DC and Boston with any major city you could want, but it's a big commuter train and not as pretty for the kids. Something like the Vermonter would have a very "we're taking the train to a winter wonderland" aesthetic, but if your kids like trains/cities then the NE regional is cool because the whole ride is "Look at those trains! Look at that city! So much industry!"