[inkista]

While the 17-40 is a good choice as a walkaround, it's f/4 and has no IS. The 15-85 IS USM looks like it's built and designed more along the lines of the 17-55 f/2.8. The 17-55 is probably still the better lens, and of course, it's f/2.8 vs the much slower 15-85, but I think waiting to see what the reviews on the 15-85 look like seems a good idea. The range is very nice, and if you don't need the speed for available light/action, it may be worth the high pricetag.

The EF-S 18-135 IS, otoh, is cheaper than the 15-85, and looks like a better fit than the 28-135 IS USM on a crop body, but it's a smaller step up in optical quality than the 15-85. Might be another option, though, if the pricetag on the 15-85 is too high.

The 16-35 f/2.8L II is also a nice piece of glass, but the range may be too limited if you're used to using the 28-135 as your walkaround, and the pricetag's kind of astronomical. You might want to consider looking for the MkI or the 17-35 f/2.8L used instead. Not as sharp, but less expensive.