I carry 4 lenses and a teleconverter when I travel with my 5dMkII:
1 EF 100mm 2.8 USM
2 EF 50mm f/1.8
3 EF 24-105mm f/4L IS USM
4 EF 70-200mm f/2.8L IS USM
5 EF 1.4X II Extender
6 and a Gitzo CF tripod
Lowepro Fastpack 250
This rig gives me a macro lens, a fast lens, a carry-around lens, a fast telephoto lens, a portrait lens, and up to 280mm focal length with L-ish quality throughout.
With the high-iso of the 5DMkII, I now drop the nifty-fifty. IMHO I think you'd be hard-pressed to come up with a better, more versatile rig with fewer lenses.