Speaking from experience, a window is the last thing I want in my snake room, unless it faces north. I have skylights on my "bonus room" - they are covered this time of year to cut my electric bill. Use non-heating energy efficient LED lighting in the enclosures instead.
I'd want tile or vinyl flooring that can get wet.
I'd want a floor drain to make clean-up easy (hose it off).
I'd want an adjoining bathroom set up with a large sink, toilet, walk-in shower, and storage.
I'd want a wall outlet every 2-3 feet and at least two breakers on the room.
I'd want easy access to the outside because moving racks and stacks up and down stairs is a PITA. Think walk-out basement.