OP, I usually start searches on Amsnag and that matrix identifies any SO sleeping accommodations pretty well. I was just checking this morning and there's still some cross country bedroom sleepers available for the Thanksgiving holiday and Christmas. Wide open next year, pretty much. Also, when using the matrix to go to Amtrak, it directs to the 'old' Amtrak matrix where one clicks on the 'buy room' button to see rooms, rather than the new matrix that has the different ticket options with sleepers as 'premium'.