Hi A Annie regarding your question about train experience my recomendation is for you to considere how many hours is the trip, specially if you are with small kids.
I once took the train from Orlando, FL to New York, NY. This specific trip took 15 hours; so we booked a private cabbin with private bathroom and TV. The train left Orlando at 4 pm and arrived at Penn Station at 9 am next day. Due to the fact that we had the cabbin we were very confortable and very rested and had a great time; but, talking with other passengers that were not in private cabbin they didn't feel the same. The train also had a food/bar carriage and restaurant carriage. This was the AMTRAK experience. Do note, that for us the savings were only US $ 100 oposed to taking an airplane.
In Europe my experience is with the EUROSTAR, Paris --> London --> Paris and also had a great time, this is a fast train so the trip wasn't too long. Also with all comodities: Food bar etc. No private cabbien this time but didn't need it. This trains is not cheap; but it is fast and it also goes to DLP, I think.
So, as final recomendation is to consider traveling party, Kids/elderlys, and like I mentioned before How long it takes.
Considering that at the time of your cruise it's still summer nightfall will come late so the views and the beatiful contrysides will be awsom. This is defenetly a capital PLUS.