I did too - did the SF back to NYC leg that goes the north route as well. Amazing experience. I was only 19 at the time. My favorite memory is that on the westbound leg we met up with the eastbound one in (I think) Yellowstone and while parking the buses they managed to slowly crash in to each other (just a dent, nothing serious). I liked the fact they both started from separate coasts and ending up colliding.
Can I ask what year that was in? Several people in here seem to be intimately familiar with this company, but it's my first time hearing about it, despite me being quite interested in travel and all sorts of weird transit methods. It made me wonder if everyone here used them when they were at their peak many decades ago, or if this varied.