I would never, ever, ever fly from NYC to Chicago (yeah, I know. This is really tempting the universe to coerce me into doing this now). 12 hours is _definitely_ faster than driving it, and I actually kinda like train travel (except that one time on Amtrak in my childhood when I was stuck in a car with the heater stuck on to about 80 degrees. _That_ was miserable.). Even with a child (haven't tried it with children, plural. Yet.). I loathe airports. I don't recall every flying out of NYC (when I've flown in or out of the area, it was either through Albany or Newark). I'm _really_ the wrong person to have an opinion about this. But that never stops anyone else, so why should it stop me?
Let's say I was leaving one of those cities to go to the other of those cities for work. I'd want to arrive early enough to get in a full day of whatever the hell I was doing, and leave some time after I was done, which might or might not include a working dinner. I know from flying out of ORD that you can easily take the train to the airport, and it is definitely cheaper and easier and on occasion faster than a taxi (which is to say, I've left a restaurant in Chicago with coworkers to head to the airport, I took the train, they shared a taxi and I beat them. And not by a little, either.). It would sort of depend which airport you were using in NYC in terms of transportation to wherever you were in the city to and from the airport. But it's hard to get around having to get there in advance of your flight's departure by whatever number of hours those idiots are currently requiring. Let's assume it takes between 1 and 2 hours from when you step out of your office/home/etc. to when you arrive at your gate, but recognizing it may take more like 3-4. The flight is going to take 2 hours. You've blown half a day, basically, flying, and there isn't enough time on that flight to even catch much of a nap. On your return home, you probably get to sleep in a familiar bed, but you got out of that bed damn early on your way out.
Contrast that with the following: the night before, you finish dinner with the fam (or coworkers, depending on your life/work balance), expend some amount of non-rush-hour time to get to the train station in your city of origin, board the train, do a little computing, maybe have a drink, and then off to bed in your berth/compartment/whatever. Awakening 8+ hours later, you have coffee and breakfast, disembark, and head into your first meeting (or, arriving a bit early, maybe grab a shower before the first meeting). After a long day (possibly including a working dinner and drinks), you reverse the process. No sleep lost here -- unless you pull an all-nighter working on the train one or both directions. You arrive in plenty of time for work the next day, or a weekend with the fam. The big loss would be sleeping in your own bed on the second night.
Possibly you lose some additional family time on night two -- but only if your family stays up really, really late.
Does this sound marketable? I suspect it isn't, because the mythical 2 hours by plane versus the really pretty close to reality 12 hours by train is just too big a contrast. And in order to have the berth to sleep in, you'd be paying a lot more for the train trip than the plane trip. But it does sound like an enchanting option.
I can't help but think that wandering about the country by sleeping on the train and waking up in a new place to explore would be hugely more fun than flying or driving. It's gotta be, or the Eurail pass wouldn't have entered into legend -- and that didn't involve a compartment. I've never traveled further by rail than Vancouver BC to Calgary Olds, and that was a blast.