I would prefer Amtrak over BUS! Never again bus from coast to coast! I had great experience with Amtrak coast to coast five times. My wife had great experience moving with me though Amtrak!
Plane is ok if I am in hurry or can afford. I found Amtrak tend to be the cheapest if you know how to get bargain! I know the secrets of Amtrak, cause I use them alot in the past.
I hope this year, will go on Amtrak with my family from coast to coast visiting relatives and my company's headquarter. My son will be super thrilled about it.
If you want to know which Amtrak route is best,
I would recommend "The Empire Builder". Damn good railroad!
I hope this year it would be California Zephyr.
The scenery is awesome on the "Empire Builder!"