DH and I stop flying in 94 after very bad experience. I will not fly again for any reason. We have been taking Amtrak every year to Disney (sometimes twice a year). I also travel for business and only go by train.
Best part of Train
You meet a lot of nice people
If you like to lay back and relax you'll love it
The dining car is very nice
Also has a lounge car you can sit in
The coach seats are pretty comfortable
Some attendents are very helpful
Worse part of Train
Some attendents are terrible
The bathrooms in the coach train are always dirty and smell
Traveling Tips
If you can afford it get a sleeper. The standard one is a good size for you and your son. It has a bathroom in the room (not closed in though) But it is clean and doesn't smell. You also have more privacy.
Take books, games, and things to keep him occupied.
Take a small cooler (maybe one on wheels) if you want to take your own food and drinks. Food on train is expensive.
The train is always late for various reasons. CSX owns the tracks and sometimes Amtrak has to yield to them. In heavy rain the train has to slow to a certain speed.
Coach section is very very cold, bring a small blanket for each of you, also small pillows. Don't worry about looking odd. I have seen people with trash bag filled with blankets and pillows. It's a long long ride.
We took coach the very first time we rode Amtrak to Florida will not do that again. Mostly because of bathrooms. Now we only get Deluxe sleeper. It has private enclosed bathroom and is very comfortable. It's very expensive but I just consider it one of my vacation perks.
In sleepers you can control your own thermostat and meals in dining room are included in price
Have a great time.
