Hi Barb,
Amtrak was not too bad, although I had a tough time sleeping. If we did it again, I would get a sleeper car. I saw many people who seemed to sleep well, but I just couldn't get comfy even though the seats are very roomy and recline back with leg support. If you do go Amtrak and don't get a sleeper...bring blankets...it gets chilly. YOu might also want to invest in some travel pillows because the ones Amtak hand out weren't so great.
The food was good...a little on the expensive side.
Luggage...we came out of Boston and there was no checked baggage, so we carried it all on...2 large suitcases, one smaller suitcase, a stroller, and 4 backpacks...there seemed to be plenty of room, but you had to carry it all on and off yourself. In DC, you can check your bags with out a problem.
The ride to me was very long, but my kids 8 and 2.5 at the time had a great time. Bring books and travel games to keep busy...although the lounge car sometimes shows movies. They try to keep the families with young children on the same car on the long distance trains (out of DC down to Florida), so if you have young kids you'll probably be with many.
Train into Florida was early, but going home we missed our connecting train in DC because out train out of Orlando was late.
Have fun...and if I can answer any other questions for you, just ask.