The 17-55 2.8 is also a nice choice for fast glass but for me personally, I would not spend $1K for a lens that I could only use on a crop sensor body unless you never plan on going FF
yes, I would agree with this as well. one lens that pried me away from this theory was the 15-85 EF-S lens, well under a grand and razor sharp even compared to the 16-35 mkii (I own both). See for yourself at http://www.the-digital-picture.com
Choose Tools, ISO 12233 then do a compare with the 15-85 and the 16-35mkii..note the edges about the same. It's quite possibly one of the best (if not the best) EF-S lenses canon makes. I use it as my main walk around lens and you can see from my arsenal (in sig.) I do have a decent selection to choose from. My alt. choice if I had it would be the 24-105 just too duplicitous at the moment. if I dump the 7D then the 15-85 goes with it and "hello" to the 24-105.