Your site's reviews of Canon EF-S lenses is missing one of the most useful, versatile, and supposedly most high performance all-around lenses, the Canon 15-85mm IS .
That should be a great walk-around lens and is the widest Canon EF-S zoom to incorporate IS, very useful for all handheld video and many stills situations, too, of course.
As a pro newspaper photog, I appreciate our great 2.8 and/or L-series glass, but the 15-85mm complimented with one of the two nice 75-300mm IS options should be a great and relatively compact travel kit, especially for people who shoot handheld video or handheld low-light stills in slower subject situations. Perhaps add a 1.4/1.8 wide or normal prime (or two) for some trips.
It'll be interesting to see how the 15-85mm IS compares to the Canon 17-55mm IS and the others :)