Quote - One thing, I've found that photographic backgrounds, ie. photos of real scenes, just don't look good with 3D renders, possible due to lighting issues - direction, intensity etc.

Photographic backgrounds CAN look good with 3D renders - but only if one matches the background's perspective, camera focal length and lighting.  Below are two examples that I think prove this point:

http://www.renderosity.com/viewed.ez?galleryid=1059839

and

http://www.renderosity.com/viewed.ez?galleryid=834541