If you have two bodies, or can change rolls with time of day, you should probably take a high-contast film (Velveeta, etc) for midday or in the shadows, and a softer negative film for early/late in the day. I shot some Velvia in 120 last time I was there, and while the chromes are beautiful, the shadows just drop off a cliff late in the day; i.e. if my highlights still have detail, the shadows are black and unrecoverable. Works well when they don't dominate the image, less well so on people or large areas. On the other hand, I have some sandstone in open shade pictures, and the Velvia gently pulled the various reds in the rock apart, revealing them all in their personal glory.

Good luck, this time of year. Light is nice, but it's getting warm.