The Northeast corridor is one thing, but the rest of the country has an entirely different experience with Amtrak. I once took a train from Pittsburgh to Chicago which was scheduled to depart at 8 AM. Instead we ended up boarding at noon, and apparently this is a completely typical delay. I hate airports, but the unimaginable volatility of Amtrak will more than erase the benefit of not trudging through airport security, as well as make it impossible to schedule any connecting transport at your destination.

As for the view, the California Zephyr is indeed breathtaking between Denver and Reno, but prepare to spend a night sleeping in your seat or on the floor of a rattling traincar (sleeper cabins exist, sure... for ten times the price of flying).