I've only taken one US train trip, Amtrak from Portland to Seattle and back. apparently something was done a few years back to reduce the contention between Amtrak and Union Pacific, the freight line in these parts. so it's about a 3.5-hr trip, potentially the same as driving but without the hot mess of I-5 in Seattle. I'd do it again.
but to the point about needing high-speed rail, man, no kidding. not only does Amtrak take forever to get anywhere far away at max 75 mph, but if you want to lie down in a bed, you're forking over a ton of money.
another thing that seems like it would be annoying but which would probably straighten itself out if rail travel ever actually became popular is that rental-car businesses don't have locations near most Amtrak stations (even in larger cities), so once you get to your destination, you still need a Lyft or whatever to the rental place.