Agree with everyone. With a nice tank and shop lights, raffelsiana and bicalcaratas have done well for me. I had a N Red Leopard cutting in that tank and it grew 3 or 4 pitchers before I took it out and the original plant that I took the cutting from has never grown a pitcher sitting at the window and they aren't lowlanders (that I know of).
It really does come down to conditions. I have a large southern window with two big silver maples out front and the freakin' roof eaves sticking out blocking even more sun. The heat/AC vent directly under the window may help or may not. Someone with an equally large southern window but no eaves to shade it or no giant trees in front would probably have happier plants than mine due to the extra light. On the flip side, I have neps outside in the front so these big trees shade them during the middle of the day.
I also keep the humidity level in the house fairly high while others report readings in the 20-30% range. Macamus3's list is a good one, but may need a tank for some. Several intermediates do well in the lowland tanks as well.
Just drop several grand and build two large greenhouses on a patch of open land. Heat one for lowlanders and set up heat/cooling in the other for highlanders. Simple as that! You'll have gorgeous neps in no time.
Or move to Borneo and set up properties at various altitudes where you can just grow them outside.