I like the Antec 900 case. The cooling is great - not just the CPU cooling, especially with the big fan on top, but the hard drive cooling. And while I am not particularly fanatical about cable management, the 900 does need a little help.
"A little help" in this case means cutting three holes in the motherboard tray: one for the 12 volt CPU power cable - enlarged to be able to remove an HSF backing plate without removing the motherboard, one for the PSU cables and control & data cables down toward the bottom, and a third above the two pre-cut holes.
And after installing the components:
The only thing that I would do differently is to make the hole for the PSU cable a little smaller and cut a small separate hole beside it for the control and data cables. The lower right corner is pretty congested.
Nice mod! Proper cable management is always a rewarding process in the end! I did something similar on my Antec 300. I used various sized holesaws to make my holes and grommet strip (edge moulding) to stop the cables getting damaged. I don't have nearly as much stuff in my case as you though so mine was a fair bit simpler! Is a full tower case on the agenda for future investments?