Get a gorilla rack from CostCo
The only terribly frustrating part is that you have to haul the cages forward in order to get into the tops of them.
Another option is the dual 55 gallon tank stands at PetSmart. They have enough room above the bottom one to get into the tank still.
And another option...build or buy stackable pvc/melamine/whatever cages that are front opening. That way there is no space lost between cages, no moving cages to get into them, etc.
And yet another option that kind of goes with the above is buying Vision Cages. Although I have heard tell that the larger ones sag in the middle when stacked. And something that I have noticed personally, if you are stacking them at all, you have to unstack them in order to change the light bulbs on the top. Ugh again.