On my last double deck layout, the lower level was at 40" (18"-24" deep) and the upper was 60". (only 12" deep) I think the higher you go, the shallower the layout should be.
Well I am not into photography on my layout (yet).I am glad everyone is asking these questions because it is making me think further down the road.Like I said I am not into photography yet but down the road I might decide to so I want to be able to do it without complications.And as far as the little kids go,they will eventually grow up so I guess providing a stool for now would be ok instead of having it too low and regretting it later.