I like the entirety of "DC Comics Guide" series of how to books. While reading the one on working digitally, I found that the artist used Sketchup to make the backgrounds on some of his comics and even the background for the cover art. I was intrigued and downloaded Sketchup on the spot. Unfortunately for me, 3D is not my forte, when attempting it I usually end up confused and grumbling loudly at my computer and breaking the model I'm trying to make. I keep at it though, and eventually forced myself to watch enough tutorial videos to get to the point where I could make something worthwhile.
I'm now using Sketchup to do my backgrounds for Twin Crowns. At first it was going to be typical fantasy fare, but then I realized it would work much better with an arabian feel, so I ditched the sweeping staircase entryway I had started and opted for something a lot more ornate. Days later, this is what I've got.
I really hope I can do a proper coloring job that does this thing justice. The thought of doing this same process for all the rooms in the game is both overwhelming and exciting.