Let me preface this question with a little info about my approach to shooting weddings. I'm mostly an available light shooter and I primarily use and enjoy working with prime lenses. Currently I have a 5D Mark II with a 28mm f/1.8, 50mm f/1.8 (f/1.4 is on the way) and an 85mm f/1.8. I also have a 40D with a Sigma 18-50mm f/2.8 and an additional 50mm f/1.8 as a backup...and when I say backup, I mean they rarely see action. I've tried the whole two camera approach and just can't grow accustomed to it. Now my question...I have a little bit of room in my budget for another lens and I'm looking at a few zooms. While I like using primes, sometimes I just wish I didn't have to switch out lenses as often when poor lighting isn't an issue. The two I'm most heavily considering are the 70-200mm f/4 IS and the 24-105mm f/4 IS (To the 24-70mm supporters, I've opted against that one because the added range is more important to me than that extra stop). I'm leaning a little more toward the 24-105 at this point, because while it doesn't really give much of a boost to my current focal length range, I feel that could actually serve as a positive by keeping me in familiar territory. Most importantly, it gives me what I'm looking for--the ability to change focal lengths more quickly. On the other hand, the 70-200mm does the same thing and has the added benefit of allowing me to stand farther away from the action. Thoughts?