I'm oftentimes asked during a workshop, "what lens should I use." My standard reply is to bring them all if you can comfortably carry them. Why? You just never know what composition you may find. Many would think "wide-angle" when it comes to photographing the Grand Canyon, yet I reached for my 70-200mmL to compress the ridges for this scene - you just never know!
BTW - I have just posted my 2013 dates for my Northern Arizona Workshop. If you are interested, please click here: http://www.donsmithphotography.com/3/Asset.asp?AssetID=18136&AKey=J5ADJ6V2