I think I'd only want a window if it's like this.First version: It looks ok, but I wish the glass window is bigger (not possible due to the radiator shroud).
Second version: I don't like the fact that the side panel sticks out, it looks kinda like a case mod (also, I prefer I/O on the side)
If I had to chose, I definitely prefer the first version, also because it features the new case feet.
Anyhow this one below is hands down your best design so far (imho):
I hope this will be the case I'm going to buy.
Solid side panels with a window always look cheap and tacky... So the options given by Dan is not in my taste, so I'd probably buy without any see-through panel.
HOWEVER... This quoted image doesn't work, because in it there are holes in the side panel, meaning the tempered glass would have to be even thicker.
One option around it is to only have two bars, one on top, and one below, OR one at the back and one at the front, for the screws. Then the tempered glass panel would be glued onto those, or have some sort of fastening mechanism.
The other option is to go with acrylic or polycarbonate, BUT it has to have some sort of treatment to remove all it's static electricity (so no dust particle build up), and be scratch resistant (and not be shipped with already existing mini-scratches).