Cross country rail journeys will always be the domain of weirdo railfans (I say, having ridden many of them many times). Flying is just too economical past the first few hundred miles.
However, we live along the Surfliner route, and for weekend trips it's fantastic. It's a 1-3 hour penalty versus driving depending on which city we're going to, but the kids vastly prefer it because they're not strapped in and we can all interact.
The US should focus on medium speed rail (100-155mph). It is easier to upgrade existing track than build new high speed track. There are lots of routes that aren't worth doing for HSR but would be at slower speed.
Good example is the Amtrak Cascades which reaches 80mph. The rolling stock can reach 125 mph. High speed rail would be nice, but Portland, Seattle, Vancouver may not be big enough to support it.
I disagree. The US should focus on those routes that there is ample reason to believe there would be high demand for true high speed rail (280km/h average speed including stops). DC to Boston Via NYC for example: there is every reason to believe this could pay for itself running 8 trains per hour all day. Once we have that there are lots of other cities that can be connected and as the network grows the whole becomes more useful. East of the Mississippi the US is about as densely populated as Europe.
If you already have a route in place using that is cheaper, but often you are stuck with decisions that made sense in 1850 when trains didn't go very fast. Where you are building new track is should always be build to 350km/h standards (you run at 300km/h, but build to a higher standard just in case you need to run fast to make up time at the cost of efficiency). There are many towns with populations of 50,000 or so people that you wouldn't build new track too, but if there is existing track running slower trains make sense.
The US is physically big enough that coast to coast would probably always be a fairly niche pursuit. New York to SF, say, is about 4700km. At 300km/h, assuming no stops, that is 15 hours. Most people won't want to do that.
Seattle to SF, however, is only about 1300km, so a bit over 4 hours under ideal conditions. At that point, it's probably quicker than a plane (no need for the whole getting to and from the airport thing, or the security, or the inevitable delays).
However, we live along the Surfliner route, and for weekend trips it's fantastic. It's a 1-3 hour penalty versus driving depending on which city we're going to, but the kids vastly prefer it because they're not strapped in and we can all interact.