24-105mm for party functions?

I know that everyone recommends the 24-70mm for weddings. But how about for birthday parties where the host still wants a bunch of shots, but doesn't necessarily need to "perfect" (as in weddings). Would a 24-105 be ideal for situations like this?

These parties would be in similar places as weddings, but mainly include candids, pictures of the entertainment, guests being entertained, and of course the cake shot.

My thinking is that instead of having to carry around two cameras with a 24-70 and 70-200, I could just use the 24-105 on either a 30D or 1Dmk2.

The 24-105 is a very high quality lens with excellent IQ and ample reach for most party environments at the long end, especially on a crop camera. IS on the 24-105 will allow slower SS or lower ISO, as situation demands, than is possible on the 24-70 in spite of the one stop slower maximum aperture. The only thing that you really give up is the better bokeh of 2.8 vs. the 4.0. You can expect to be well pleased with the IQ of the 24-105.

I've used it for parties and indoor events with excellent results. Be aware, however, that IS does not stop subject motion, so while it works pretty well for static shots, with slower shutter speeds, you will get blur if your subjects are moving around. Of course, a good flash can remedy that problem.

Also set your ISO higher if your IQ demands will allow. Using the 24-70 @f/2.8 also may not be possible (DOF is shallower) depending on the environment, so the minimum f/4 on the 24-105 should be fine. I have the 24-105 and find it to be an exceptional lens. Finally I've often found that capturing an image that is just a bit under-exposed (via shorter exposure time) by a stop or so can be remedied quite well if shot in RAW.

Thanks for the feedback. Just bought a 24-105 here in the classifieds. I have my Tamron 28-75 2.8, but planning on selling it, the kit lens, and 50 1.8, and maybe the 20D just to get a little more organized. I understand about the IS not stopping movement, but I try not to shoot at 2.8 on the Tamron in the first place. Hoping that the 24-105 is sharper at 4.0 than the Tamron is at 3.5...if that makes sense.