Well if the question is what is the difference between the upgrades you're considering, I'd break it down like this I own both the 7D and 60D APS-C camera's as well as the 5D mkII, to be honest in terms of IQ they are pretty close,
For action(in your case kids playing) the 7D would be the best option this is a fast camera, it focuses better than either the 60D or 5D mkII oh and BTW the 60D is faster than the 5D.
For landscape and setup shots to be honest any of these cameras will blow you away, but the winner here of course would be the FullFramed 5D mkII or even a 5D mkI which are selling for about the same as the 60D.
Now if you want to be more creative with your camera the 60D is the ticket, the articulating screen really opens up the shot possibilities.
You already have some great glass so any of these camera's will give you more detail and IQ than your current XTI, but ultimately like anything you have to feel comfortable with the tool you are using so my suggestion would be to head to you local camrea store and try them out the 60D might surprise you it's a very well balanced camera, and gives you a cross between the other 2 don't let the lack of Micro Adjustment scare you, I've never had to use it with any of my lens, by the way the 9 AF points on the 60D are all cross type with the center one being F2.8, so again a very accurate camera.
Hope this information helps and good luck, you really can't go wrong with either choice.
