I'm probably not alone in wishing Canon would make a really nice "walk around" lens in the med wide to med long range. A Pro/semi pro lens, in say an EF 24-250, fixed f4, USM, IS, "L" package, would be very appealing to me. Right now I use a 24-105L for this purpose, but often feel the need for a little more reach without having to carry a second lens around, thus defeating the one-lens idea. I love my 28-300L for the one lens carry idea, but it becomes a real drag "no pun intended" after an hour or two on the trail or street! I used to use my ole 28-200 in the film days as a single lens carry. However, it just doesn't have the quality of glass needed for today's pro digitals. My short answer fixes right now, are to carry a 1D4 with the 24-105L on the body and my 70-300L in a small pouch. One of the things I really like about the new 70-300L, is it's compact size and light weight! My other fix, especially when changing lenses is out of the question (weather/environmental conditions prohibit it), is to carry a 5D2/1D4 with the 24-105L and another 1D4 with the 70-300L lens. This isn't the answer to my one body carry ideal, but it works OK, as long as I'm not walking too far!