If I had to only have four cams, they'd all be camalots b/c they have the widest size range. I'd also supplement with tri-cams, b/c even though they're a bitch to place they fit in pockets and parralell sided cracks - where nuts won't. They're good for the mountains.
Also depends on what the rack's for. For just rock I probably wouldn't bring any pins, but if you're gunna be swinging ice tools you should include some angles and bugs. You can also hammer the shit out of a nut to fit in the funky spots.
And don't forget me frosted lucky charms, they're magically delicious!