Maggie,
Have you read the reviews on this site? My personal experience is limited as I broke my 24-70 f/2.8 last week and have a 24-105 f/4 IS until my lens returns. So far I can say that it is light compared to the f/2.8 lens. The stabilizer is very quiet and is effective in low-light situation. I find that the zoom and focusing rings are not as smooth as my 24-70 but it is a brand new lens and I expect that it will loose it "tightness". The lens hood is smaller and not as clever as the one from the 24-70. It moves as you zoom whereas on the 24-70 it stays in the same place. As others, I've noticed that there's distortion when use in the wide-angle range, at least on a full frame camera. On my other body (1DMk2), it's not as severe. You'll have to see if you find it objectionable or not for your use.
Auto-focus is fast although I feel it's not as fast in low-light as my 24-70, but it's more of an impression than real facts as I can't do side-by-side comparison. I like it but I'll keep my 24-70 if it is correctly repaired.
Others may have a different opinion but I think it's a more do-it-all lens than the 24-70. In your case, I don't think you'll regret the 24-70.