Scratch the Tamron 24-70 and get the Sigma 28-75 f/2.8 XR Di. This is a great lens. I own it. I would recommend against spending big bucks on the Canon equivalent.
http://www.photocamel.com/index.php/topic,955.0.html
http://www.photocamel.com/index.php/topic,5771.0.html
The telephoto zoom may be a different story. I have not used the non-Canon lens you refer to, but the fact that the Canon version has IS would make me look closely at this one if I needed that range, which I do NOT. I find the 70-200 range to be neither here nor there, either too short or too long for my typical photographic purposes. The Canon version is a very heavy lens, too, so you have to be willing to lug it around.