JDM von Weinberg , May 11, 2013; 08:57 p.m.
IMO, the 24-105mm is the "best all-purpose lens" for the camera, especially when combined with the 100-400mm and the macro.
I accept compromises are necessary, but the wide angle to 300mm compromises are more than I personally would accept. When you don't want to switch, assess the situation and leave either the 24-105 or the 100-400 on the camera for the shoot.
All you need is a ultrawide lens and you're set for broad-view, bear, or bug.