And that Canon 24-70 is a tough workhorse. If you are going to put it to work, just get a used mark 1 on on Ebay for $1200. Then save up for a 70-200 F2.8 IS - the first one is fine. Those are must-haves for weddings, from my experience.
I will say that Tamron 24-70 does sound nice with VC on it. VC will come in handy during weddings.