Arnold,
With the advent of modern O gauge speed control (MTH PS2, PS3, Lionel Odyssey), DCS, Legacy and scale-sized O gauge locomotives and cars, it seems to me that the emphasis has become running at realistic slow and medium speeds rather than high speeds – perhaps because most home layouts are not large enough for realistic-looking high-speed running. Other than my Amtrak AEM-7s, or maybe GG-1s, I don’t have any model locomotives whose prototypes ran at more than 100 MPH. Nonetheless, when running passenger trains on my O-72 layout, I always give them a short run at “high speed,” say 80 MPH, as in this video of my MTH PRR G5s #5740 with PS1. It may not be realistic on the curves, but I like to hear the (steam) sounds, blow the whistle, and see how a train looks passing through the countryside at 80 MPH - a speed the G5s locomotives did attain on the LIRR.
As far as the real thing, I would like to see the investment and construction of modern high-speed rail in the United States. I enjoy travelling on Amtrak’s Northeast Corridor at 125 MPH. And there are city-pairs in the US where high-speed rail would be feasible.
My first step will be to have an O gauge layout large enough to run an Acela at 150 MPH... 
MELGAR
