If color slide film, I'd take Kodak E100 with a colorless UV filter, if color neg film, Ektar with a 1B pink skylight filter in order to counterbalance its excess cyan response as well as cut distance haze. Portra 400 would be more forgiving, but grainier and not quite as well corrected for certain hues - after all, it's marketed for portraiture (Portra = portrait), so still has some tendency to lump other warm neutrals and earth tones into "pleasing skintones", rather than cleanly discerning them.
For b&w Acros, nothing deeper than a 25A red; but a medium deep green filter is often more helpful in the Southwest for toning down reddish sandstone hues, while bringing out clouds in blue sky at the same time. A deep yellow, orange, or red filter often makes reddish sandstone look annoyingly bright and paste-like in a print. I personally have no use for polarizers or ND's; but some people obviously like them.
Lens / perspective selection is more of a personal matter. And I can't personally imagine being without some kind of focal length longer than 50mm, although I admittedly have never shot 35mm in the Southwest, but only large format and medium format gear, and with numerous types of film on many occasions, so I have a good feel for the area in general. A very short wide angle lens is less likely to capture a wide sweeping vista as to simply shrink the background to next to nothing while dramatically exaggerating the foreground. It's a matter of style; but the Grand Canyon involves not only big scale, but a lot of sheer distance too, and much of that will become almost invisible in an extreme wide-angle shot. Maybe down inside some cramped canyon one of those extreme wides might come in handy, maybe not. Just sayin' ...