Well, it looks like we all set for an Phrag set as well! Hehheeeheee ...

Regarding the rooks and knights, I think we still have quite a few fantastic multiflorals left. For instance, Paph. parishii with its top-heavy dorsals and ultra twisty petals would make good rooks, kolos are definitely knights materials as you said before. What do you think of Paph. praestans? Great yellow color!
There are other great paphs in other groups like Paph. tigrinum, beautiful flower there! Paph. bellatulum is another great one for a separate paph chess set. We could think of a white set and a black set as well. Stonei as queen for the white set and Sander as queen for the black set. If we do that, we can add tons of other great paphs into our chess set(s) like our productive phil (pawn for the black set?) and maybe even some parvi!
Cheers. Hoa.