I'm just back from Taiwan, where I rode the High Speed Rail. Each coach has assigned seating (2 x 3). When buying tickets on-line, at a vending machine, or through a ticket agent, you are assigned a specific seat. This is true for trains that have more stops and more frequent "on and off" passengers than Acela's typically do. The system seemed to work fine - I was always assigned a row by myself if space permitted. So the software is out there - and proven. Amtrak should look into it.

And a further thought on Acela F, the seating should be configured 2 x 1 the entire coach, with no fixed tables. That will permit easier seat assignments, and no crazy rush for the "good" seats. Eliminating the tables will also quiet down the F car, since there will be no foursomes having an on-board party. While they're at it, they should re-engineer the tray tables by having them come out of the seat's armrest like airlines do. That way your tray table won't bounce every time the person in front of you sits down. (I once had a glass of wine spill all over me when that happened - and the train wasn't even moving!)