Larger doesnt always mean happier. A lot of snakes are actually stressed when put into too large a cage. I personally prefer racks but then again I dont have my snakes for display. If I wanted to display my snakes I would definitely look into the vision or animal plastics cages. They look great are stackable and the plastic will ensure that they last forever as long as they are not abused. Also its a lot easier to pick up a plastic cage for cleaning etc. than it is to pick up a glass tank or wooden cage. Plastic or pvc cages also hold humidity in very well. Below I provided links to two very reputable dealers. There are many more but these two are the only that I have experience with.
http://www.animalplastics.com/
http://www.visionproducts.us/htm7/cages.html