As far as setting up closer to keys vs. guitar... it depends on the players. I like to be physically closest to the best players in the band whenever possible, and I ask for my monitor mix the same way. If the keyboardist is kickin it with the drums and staying out of the lower register, I want to hear a lot of that cause it makes my job easier and more fun. OTOH if s/he's going to be pounding out lame bass lines out of time, it is literally just noise. Same with guitars, whether acoustic or electric. Even singers. I've asked sound techs to take the vox completely out of my monitors more than once.
