It is obvious that you put a lot of thought into this cage.
You inspire me to add a second floor to our present cage.
Susan... if appears that the cage is sitting on *something*. Is there something that is under the cage?
We have a cage that is built on a plywood and 2x4 wood base with wooden legs. In order to get to a second level (to clean) we would have to use a step ladder.
Half round grids? I'm not sure what that would look like but it sounds fancy! Your cage is beautiful! If you don't want to have to use a ladder, you could cut off the bottom of your base to make it shorter so your second level would be where your top level is now.
My cage is on a regular kitchen table. The table was a little too small so we bought a piece of particle-board wood (slightly bigger than the table top) to sit on the table to make sure the cage wouldn't fall off an edge.