I have the 10-22, 17-85, and the 17-40. I won't part with the 17-40, because I like it on the 20 more than the 17-85 which I reserve for walk-around use only. I recently sold my 28-135 because the 17-85 performed that role and I also have a 70-200 and a 300
The end of this confusing diatribe is that I am a victim of having to by a selection of lenses one at a time, making compromizes to fit in my kit.
With as 20D, having to do it all over again, my choices would be 10-22, 24-70, 70-200 IS, 100 macro
With a full frame, my choices would be 16-35, 24-70, 70-200 IS, 180 macro
But wait - there's is a new 24-nn L IS full frame coming out at the end of this month! Sounds like that is right up your alley!
What's this about a new 24-105? f/4L??
Thanks for the comments. I think I love the 17-40mm too much to replace it, even though it might make more sense. At this stage I'm thinking:
And I'll consider the 17-85mm longer term: it's likely not as sharp as the 17-40mm and I'll need the 10-22mm anyway. Perhaps I might get the 17-85mm for Christmas... :-)