The tray space is really important. If you use split developers and archival fixing you need 5 trays for the size print you want. (this is my dream darkroom) I would like to do 20x24. At this time I am limited to 3 16x20 trays. It can be a real challenge at times. Room for good paper safes would be great too - I pull them out of a package and it is a real pain. -Frank