I haven’t done NJ to LA, but I have taken the Lake Shore Limited, and I tried commuting on an overnight train between NY and the Southeast, all in first class (sleeping cars).
Never again. Enough nasty employees that at some point you’ll deal with one of them, and TV dinner food, wrapped in plastic with the labels still on, on trains east of Chicago, and rattling old equipment, all at a higher price than flying first class.
It’s not worth it.
Imagine if the US had only one airline, government-funded and with a limited schedule. Just how great would air travel be?