My normal "walk around" lens is a Minolta 24-85mm f/3.5-4.5 AF lens on my Sony A700. In most cases, it's wide enough for what I shoot, unless I'm trying to get a larger group of family members in the frame in a smaller room where I may not have room to back up enough. I'd prefer not to lug around a heavier f/2.8 lens unless necessary and I like the 24-85mm focal range better for most things. From time to time, I do consider getting a Zeiss 16-80mm f/3.5-4.5 instead though.
In lower light when I can't use a flash, I'll usually switch to primes (I've got the Minolta 28mm f/2, 50mm f/1.7, 100mm f/2, and 135mm f/2.8 AF lenses), versus the brighter zooms I have (Tamron SP 20-40mm f/2.7-3.5, Tamron SP 35-105mm f/2.8 ). I like it that they're all stabilized on a Sony body, too.
A 24-70mm f/2.8 would come in handy from time to time though (so, the Sigma 24-70mm f/2.8 I mentioned looks attractive, since it tests well on a body using an APS-C size sensor).
is probably right about the reason you're seeing Sony coming out with high quality lenses like the new Carl Zeiss 24-70mm f/2.8. They want the best quality possible for full frame. Personally, I find a 24-70mm on full frame to be a bit limiting on the longer end. On an APS-C size sensor, 70mm would be OK for most shots I'd take But, it depends on what you shoot and the conditions you're shooting in.