Agreed Lamar. Another time to use Velvia would be with very flat, dull lighting, like heavy overcast, to increase the contrast and make the colors pop a bit without the over the top look of it in bright light, IF the film speed will support that. As you say, I find it a pretty narrow purpose film. I got along somewhat better with E100VS but only slightly so (and appreciated the extra stop of speed relative to Velvia 50 - I never used the 100 Velvia.)

EDIT: Oh yes, if anyone is looking for a less contrasty, less saturated more natural looking slide film on today's market and you can stand some extra grain, try Provia 400. It's a wonderful film, amazingly good for a 400 speed slide film and flatter and less saturated than 100, but it is quite a bit grainier. This is a photo of my wife shot on our honeymoon on Provia 400:

Alicia_Kite1_LowRes by Roger Cole, on Flickr