Honestly, I took a train to Colorado last year and it was the best decision. You skip the airport stress and get to see incredible scenery, like the Rockies, right from your window. It feels like the journey is part of the vacation.
Planning it was super easy, too. I just used a site like FaresChoices to book my Amtrak ticket. It was straightforward, the price was clear, and having that part sorted without any hassle made the whole trip feel relaxed from the very start. Highly recommend it