Nicole,

There are a few factors to consider, assuming you go for film :

Scanning at home?
Printing via lab
Contrast of your locations?

If you are scanning at home, a home scanner normally struggles to pull detail from very contrasty films such as Velvia, if the shadows are dense. Therefore Velvia, the most popular choice amongst landcsapers might not be a good idea. many swear by Astia for scanning, which is less contrasty by far. It is also less saturated, but this is an easy fix on the computer.

If you are printing via a lab, then you can choose a contrasty saturated film such as velvia with no issues as their kit will glean all the shadow detail that your home kit could not...assuming the film is not too contrasty for the scene.

If you are going to shoot in average or low contrast scenes, Velvia IMHO is without parallel. I personally far prefer the look of Fuji chromes and would choose velvia 50 (not used much velvia 100f and none of the new velvia 100) 100% of the time. One other bonus of the old velvia 50 is that when shooting at long esposures, it has poor reciprocity and colour shifts which can be rather nice! If the contrast is really high, steer well clear of Velvia and go for Provia or Astia.

My Choice? Take some Velvia and Astia covering both ends of the scale. IMHO print film is miles behind in terms of image quality.

Tom