A 120-gal glass tank will take a bit of work and modifying to get it set up correctly, compared to maintaining a PVC enclosure. I have a 120-gal aquarium with home-built plexiglass tops that have a few ventilation holes each, so that heat and humidity stays in it. Heat is done with two large UTH's (once set at 80*F, the other at 90*F) and in the winter months I use two deep heat projectors (DHP's) to bump up the ambient temp since the radiation will penetrate plexiglass and heat objects in the tank. I have a carpet python in it and he likes to perch/bask on driftwood set up under the DHP's.