Best "Walking Around" Canon Zoom...

[bigtwinky]

I usually have a Tamron 28-75 f/2.8 on my camera as my walk about lens.

 

[KmH]

Most "Best of" threads wind up in the same place.

As seen here, you've gotten a plethora of recommendations, proving, once again there is no one "best".

 

[jimmer]

I have the Canon 7D and use the 17-55 2.8 IS as my everyday lens. Takes great photos and love the constant 2.8 aperture. I would look at this lens as my primary is used on APS-C sensor

 

[FrankLamont]

Exactly (referring to Usayit and Overread's posts)... a walkaround lens is most likely (for)

a) during the day
b) walking
c) outside

...meaning, of course, that you'd want to have lightness and size taken down. Aperture is not so much of a big deal (hence mention of 'outside' and 'during the day').

The 24-105mm is reasonably light, small and the aperture isn't outrageous. And heck, if it rains and you have a sealed body... there you go, an added bonus.