I use a 36x18x18 exo terra for my biggest and most social ball python. He's 4.5 feet, 1800-1900g. The tank is huge for him. I have two really thick branches gorilla glued to the tank that he uses at night, but I think any more height would be completely useless.

The exo terra did need some modding to work for him though. I have the whole top screen covered to keep in humidity except for a square where my ceramic heat emitter is. I also have the sides half way blacked out for security.

All my other snakes are in tubs and do equally fine. I don't think a full grown ball python is going to make it to the top of a 36" tank without a loud and painful sounding thud immediately after.