There is, of course, the excellent EFS 15-85 to consider here for a general walk around lens for cropped sensor cameras .

I never chimmed in on the lens selection. For general purpose lens on a crop sensor camera great options are the 17-55 f/2.8, Tamron 17-50 f/2.8 non-VC, and the EFS 15-85. I own and highly recommend the 15-85 for general purpose photography. But, I can absolutely see buying one of the f/2.8 lenses for the lower light capabilities and better DOF. My general rule of thumb would be, for most users, if you are taking photos of kids/families, especially around the house, the 17-55 f/2.8 is probably the best option. If you want the focal length range, are shooting outdoors a lot, then I would recommend the 15-85 and use the cost savings to pick up a flash.

The OP brought up the 24-105 as a general walk around lens on a cropped sensor. I've seen some great photos from this combination from several forum members, but, similar to PatrickH, they seem to be combining it with a UWA lens such as the EFS 10-22 or Sigma 10-20 or 8-16. So, great option if you buy it in combination. For me, I like the ability to shoot the 15-24 mm range without change out the lens.

Just remember, these are all great options. Pick what serves your purpose the best.