I've expressed my love of rail travel before, but I think it's truly a shame that in the U.S., the rail system is no longer a major mode of transportation. Admittedly, I don't much like cars and I realize that rail travel is something that's a bit romanticized, but I really think that trains could help ease some of the common problems in the U.S. Plus, you can get a beer on a train and not have to worry about it.
I loved traveling by train across the States -That link is my "how to" regarding Amtrak from Ann Arbor MI to Whitefish MT
One of these days, I plan to do the length of the Trans Siberian Express: I'd even like to extend the route, taking the ferry from Sakaiminato to Vladivostok and then making my way to England. Of course, I'd want to take my time with it and would likely need to raise some serious scratch or find some other way to subsidize the trip. What are dreams for, right?