Standard walk-around without IS is rather strange idea... Ideally Canon EF 24-105mm f/4 L IS USM. If money don't allow - Canon EF 28-135 IS USM which is very decent for its price (~$300 on ebay as the market flooded w/them b/c of 40D kits in US).
I generally stay away from non-Canon optics for Canon body with some rare exceptions. Got Tamron 17-55 f/2.8... Sold it. OK lens, nothing impressive, decent quality. Within 1st day got firmware error ERR99 - never seen that w/any Canon lens. AF is bad, no IS.
Just my 2 cents,
Nikita.
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