I've never used Velvia 100F, but maybe you can find useful this article :

http://www.naturephotographers.net/a.../gt0803-1.html

I'll be in Utah at the end of this week and, for the first time, I decided to bring with me some boxes of Velvia 100F and Astia 100F other than the "classic" Velvia 50, just to personally check these films...if you are interested I'll let you know my impressions when I'll be back...

Ciao

Marco