i think your getting it backwards, singalana needs more humidity than spectabilis... spectabilis just seems to take longer to settle in and grow for some people, and i have to agree, it can be a bit of a pain to settle in and pitcher, but i think its more or less because some people dont acclimate it right.... my spectabilis north sumatra did amazingly well as a windowsill plant for over a year, then i moved it into my greenhouse after i built it... singalana, really does need decent humidity to pitcher, and IMO decent is 50%+ so your 65% humidity should be perfectly fine, provided you mist your plant (should you go with singalana) or add a nice top dressing of live sphag (really kicks up the RH IMO)
atleast they will pitcher though in moderate humidity, unlike those darned talangensis plants xD
this spectabilis north sumatra pitcher formed in whatever the humidity is in my garage, like 50% if that...is one of the pitchers from the basal that is taking over, the main vine is starting to go downhill.... flowered itself into poor health haha.