Originally Posted by
wickerprints
The EF 24-105/4L IS is not going to give you anything significantly better than what you already have. While it is "weather-sealed," it is really nowhere as robust as you may be led to believe, due to the extending zoom design. It is not impervious to dust. It is also a relatively slow f/4, which in my experience has been its greatest limitation in terms of being able to control DOF.
I think it is a very common fallacy to assume one needs to have a continuous focal length range from ultrawide to super-telephoto. That's not a very good criterion by which one should select lenses.
I belong to the school of thought that the choice of lens mainly comes down to type of photography, but optical quality cannot be ignored. Yes, you have a gap from 55mm to 85mm. But honestly, is that range so important to cover? What kind of photography are you doing such that those focal lengths are absolutely required?
If you buy the EF 70-200/2.8L IS II, sell the EF 200/2.8L. You won't have any use for it. In fact, you could also sell off the EF 100-400/4.5-5.6L IS. In its place you could get the 300/4L IS, which is much lighter and a full stop faster. Normally I'd recommend the 300/2.8L IS but I don't think you're going to carry that around much.
Do you own any Speedlites? If you don't, get one. Indoor family photography can be incredibly good if you simply learn how to diffuse your flash. Bounce it and you can get wonderful results. With the 7D, you can even make it an optical slave thanks to the pop-up flash. Don't rely on fast glass--it's not like you're taking indoor concert/event shots, or gymnastics, where flash is not an option and the 85/1.2L, 135/2L, 200/2L are the lenses of choice. You could get the 35/1.4L, which will be a lovely lens, but the problem is that it's not cost-effective--by using it on a 7D, you are not taking advantage of the primary reason why the lens exists (and costs as much as it does). The fast wide-to-normal lenses are really all meant for 35mm sensors.