I think I changed my mind about 20 times on backgrounds today. This is a tough decision to make! Because I'm finding it difficult to visualize the type of look I want, I took to the internet for some inspiration and found a few pictures.
I loved both of the above "Amazon" type habitats, especially the second. Granted, they are both public aquaria with much more water volume than I have, but seeing these made me have a revelation.
I can't even see a background in either of these setups!
If I want to maximize on swimming room for my guy, I probably need to stick with the thinnest, least obtrusive background that still provides texture and interest.
Designs by Nature Chimba
Designs by Nature Bulu
Both of these backgrounds are about 3" in depth. I can still hide tank equipment behind the background, but wouldn't lose as much swimming room as I would with, say, the Aquaterra Amazona, which takes up a lot of room in a tank. To get an idea of just how much room the Amazona takes up, take a look at R1_Ridah's thread of his 180g setup.
http://www.monsterfishkeepers.com/forums/showpost.php?p=4461639&postcount=11
I still think it's the most beautiful background that can be bought, and I would buy it if I had much smaller fish, but one of the reasons I chose a 2' deep tank was to give my fish lots of room. So the saga of choosing a background continues...