I love the 28-70 2.8 AFS. I think they make a 35-70 2.8 just not the AFS which is less. I like the speed of the AFS as well as the silence. I hate that motor focusing on the non AFS lenses.
I try to do as much natural light as possible when possible. The lens just allows so much more light in that i can use it quite often without flash..hand holding.
I use the 28-70 a good 75% of a wedding, I use the 17-35 AFS 2.8 for 15%, the 85 1.8 for about 10% and the mega 70-200 for about 5%. (The 70-200 is really too big for my little hands...other than that it is a favorite amoung those who use it.)
If you are shooting natural tung. light use the white balance on the camera, it can give you some great color effects.