A range of sizes would indeed be good. For my own use, I do not use a secondary pot..just my style..or call it my laziness
I just try to be careful when I pull my orchids out of the glazed multi-holed pot. Typically orchids are potted as snugly possible without being too big, otherwise it takes too much time for the media to dry and most orchids will not like being too soggy. Having the holes then helps a lot.