Weekend departures might be more expensive during spring break. if you have some flexibility, check prices on amsnag.net to see if you can find a "low bucket fare" date that also includes the detour.Well AMTRAK must know that these rare-mileage trips will bring out a lot of rail fans. I just looked at a March 23rd departure from Seattle and a roomette is $479 and the railfare was $177. Thats fully double what I paid for my #14 trip 3 weeks ago.
When I rode the northbound detour in 2012 there were very few railfans aboard and plenty of seats overall in coach for my LAX to OKJ journey.