How much is a 1-day rail pass?

I've had USA rail pass woes. Have you?

• After many months of research, I decided to purchase a rail pass yesterday so that I could travel across the entire USA and see it. The deal is quite simply amazing: $400 to travel over to California and back to Virginia (that would end up being 8 segments). Like I said, I had done a lot of research on rail passes and people's experience with them. I've heard that it's possible to get the tickets the day of and not pay anything else. Today I ventured up to Union Station in Washington DC to pick up my tickets early just to be safe. After telling the guy at the desk that I wanted to go to San Diego and dealing with his confusion (I don't think English was his native language), he then continued to explain to me Amtrak's pricing system (4 tiers - only 3 available for rail pass travel) and how I would have to pay extra to ride on most of the trains. The total came up to be about $100 extra each way, which makes a rail pass not worthwhile. The Amtrak website said nothing about paying extra, nor has any source I have seen on the web. Has anybody else had the same experience or I do something seriously wrong?

• Answer:

  Amtrak capacity controls the Rail Pass tickets away from the highest bucket of fares. Therefore you need to have booked tickets in advance - although usually a few days notice will suffice to avoid the high bucket, except for busy routes. It is stated in the USA Rail Pass description although often overlooked. Sometime this leads to situations where booking a roomette leads to a lower upgrade fare, since the lowest bucket fare is covered by the Rail Pass. Amtrak fare pricing is somewhat confusing, although more transparent than the airlines.