For me, it all depends on the snake. I got a 4x2 RBI cage for my BP because I love natural looking caging for pets, I like giving them as much room as I can that they will like, and I enjoy watching them explore the habitat at night.

For my corn snakes, though, because I intend to breed them I will be keeping them in tubs...but no rack unless you count the plastic shelving unit. For any adult snake, I use tubs that are totally clear(and then cover the back and sides) and have at least a good 10" of height so I can add greenery and climbing things. Even in space efficient caging, you can still make a pleasing and comfortable environment.