Our last 15 or so trips have been on Amtrak, we used to do the northeast Ohio to Philly run until they closed our station here in Ohio, so we have to drive an hour to the next closest station and that train runs into DC. No matter, we're headed south after DC, and we have done the whole trip in coach, huge room around the pair of seats, they recline, leg and foot rests makes relaxing a breeze. Bring blankets since the temps at night get really cool, sometimes during the day it's chilly too. We bring a small cooler, sandwiches, snacks and drinks but as stated above, the dining car has excellent food, club car isn't bad either, both kind of pricey but it's vacation.
We've done the roomette (sleeper) from DC to Kissimmee alot, bought once on board and meals were included. Buying a sleeper before hand can get expensive but we only need a room for 2 so we ask after we pull out of DC, if any are available you get a discounted rate but you play the odds of nothing being available. It's happened to us a couple of times out of 12-15 trips but it's worth it to us. The sleeper gives you the comfort lying down to sleep, no noise or disturbances of others, toilet and of course the meals. We're headed down again this January, 23rd, and Amtraking it all the way.