Haven't brewed a saison yet but I like De Ranke's Saison de Dottignies. It contains Challenger, Brewer's Gold, Hallertauer Mittelfrüh and Styrian Golding.. I would assume that Challenger and BG are The early, bittering hops and Mittelfrüh, Styrian are late/aroma hops. The taste is not completely different from trappist ale Orval that takes Hallertauer hops and the Styrian as well. So a lot of different varieties could be used. Just prepare a highly fermentable wort and choose a suitable yeast.