Another vote for the 17-55. It is the lens that I keep on my camera 90% of the time. For shooting children indoors, you really want 2.8. I will also say that 24mm is not wide enough on a crop sensor for indoor group photos. There was a recommendation for 35mm f/2 IS. While I love my non-IS version, I stopped using it as soon as I got the 17-55 because 35mm isn't wide enough. The 17-55 is good enough that I am reluctant to go full-frame because it would cost so much more to get an equivalent lens.