Next Lens Purchase - Recommendation

Lately I've been using my 50mm 1.8 more often, on my 40D. I love the lens, and the speed, but would like something with a bit more versatility in the "zoom" space. I primarily shoot with my 24-105 L, which I love, but would like to get a faster walk-around lens. This is purely a hobby for me right now, so my shots are all over the board in terms of type.

As of right now, I'm pretty set on purchasing Canon's 17-55 F2.8 IS, based upon my research on this and other forums/web sites. However, before I execute, I wanted to see if there are other lenses I should have considered. The only other lens I really debated, as the 24-70 F2.8L, but I'm leaning towards the wider 17-55, with the IS option.

Anything else I should consider? Thoughts on my choice?

--
Darren Greer
Canon 40D
http://darrengreer.com
http://darrengreer.smugmug.com