I have noticed some discussion of focal lengths in other threads, and thought I'd start a new thread on it rather than comment in the other thread(s).
Here is my take on it. We all know that longer focal lengths condense depth, and shorter focal lengths increase the illusion of depth. This is the reason I always use my 18-55 lens, set at the shortest focal length that my backdrops allow. I like the feeling of more depth, missing in many model pictures.
Car advertising photographers are masters at sitting right near a front fender and using short lenses to make the car look really massive. One of the things I love about my 18-55 Nikon "kit" lens is that it is macro at ALL focal lengths, not just the 55mm. end. Since my camera is a apc format rather than full frame, the so-called normal focal length is far less than 50-55 mm anyway, so I need to shoot around 30 mm just to get normal perspective. If my backdrop allows even shorter focal length (wider angle, of course) the perspective is really great. Looks like you are standing right off wingtip or nose.