I'm very fond of the L glass. I wish I had a grand to blow on one.
I'm looking at the Sigma 18-50 f/2.8 EX right now. It'* a good range for what I do. I'm pretty happy by the pics I have seen from it. I also like the Tamron 28-75, but it doesn't give me too much of a wide end, which is something that I use the most.
I tried the Sigma 24-70 EX Macro, but it was just WAY to big for my liking, and it was giving me a lot of CA. Plus, it takes 82mm filters, and those are just crazy expensive. It also screwed with the flash, making strange shadows because of its massive front end that gets in the way. I do like the 24-70 range though.