Have a look at
http://www.the-digital-picture.com for some good reviews with various comparison options.
If you have a bottomless wallet, then the new TS-E 24mm is stunning. A review is available here
http://www.the-digital-picture.com/R...ns-Review.aspx
And if you want wide, then the TS-E 17mm is also good. (The review on the above site also has a moue over comparing it to the 17-40 and 16-35mm)
Whilst Flake is no doubt correct in that the wide zooms are not as good as say Nikons (I tried the 14-24 on a Nikon D3 on Saturday, and it is stunning!) when you add all the other variables in, they are a decent compromise.
Oh, and finally have a look at this thread
http://photography-on-the.net/forum/...34756&page=214 for some stunning examples of what the 17-40 can do - there will be another one for the 16-35 too.