Think the Amtrak trains are much more comfortable. Though
Ex. If you book your trip on some non peak days, you usually
is assigned a seat, but have a whole of 2 seats all by
yourself.
You really should go to the Amtrak website to see whether you
might need to take buses in between portions of your full
journey.
And if you are asian like me, probably can slouch a bit and
sleep on the two seats.
I did most of the flights from Santa Ana Airport to Seattle
Washington by flight. Cos it takes maybe 2-4 hours instead of
a two day's journey.
I did the train journey from Seattle to Vancouver Canada, or San
Juan Capistrano to San Diego. Which was bearable because
I have cash to buy food at the canteen, bought my charger to charge
up the laptop and watched dvds, as well as listen to my mp3 or
hokkien and cantonese songs.