The problem when Business (on NE Regional) or First (on Acela) is the last car is that it becomes a much bumpier ride, combined with a crack-the-whip effect, compared to when those cars are up front, right behind the locomotive. It makes a big difference. One time on NE Regional I paid extra for business, and greatly regretted it as it was too bumpy to do anything on the laptop -- had I been up front, that problem would not exist.