Grant,
I have to disagree with your comment about, "at the end of the day, you are tweeking pixels and their RGB values. That's it."
PS and several other programs allow the user to make visual changes on the fly from a captured VW view and CS5 allows those changes directly in the 3d world. Here's a, for instance, your pitching say a 'kitchen' to a client, but there is nothing on the counter? while your at your'client's' house, you snap a couple of photos of their kitchen, with all their 'stuff'. Now, sure you can add a microwave, coffee maker, blenders, etc. all from VW or a 3rd party site. But,(Trade Secret)does VW's or Maya, or 4D have what this paticular client has? What I mean is, their pot holders, cookie jars, pictures on the wall, mail basket, key holder, etc. So Now you have hybrid PS+VW rendering with their stuff in it. Using this method, you will please the client everytime, as you have made it "theirs". Also, use the image props. they cast shadows, turn to face the camera, if you don't want to invest in 3rd party. VW comes with a pretty good amount.