I don't really like glass aquariums for larger species because they are difficult to get the snake out of. Reaching in from above can be problematic, and difficult to clean and regulate.
I recommend getting something like this with a shelving unit and some climbing apparatus for an adult carpet.
http://www.animalplastics.com/
I plan on getting the Terrestrial T10 (48L x 24D x 15H)
The 'Carpet Cage' under specialty cages would also work. They need a little more height and climbing so the extra shelf is a must.