You'll find all the permutations shown on various other posts I'm sure, but it comes down to personal preference and knowing how you live as a family. A lot of people put the kitchen in the darkest bit (where it shows dining) and I think that's because you'll have task lighting on in there so it doesn't matter so much if it's naturally a bit darker - and also to save that part of the room becoming a hallway more than an actual room (if it's the kitchen it's the destination, rather than somewhere to walk through to get to the destination). Some people like to have the kitchen in-between the dining and sitting areas, so you are accessible to both so you should also consider moving it to the current sitting area - doors/windows would have to be reconfigured for that one, and don't forget to think about access to the utility if the kitchen is moved. Once the kitchen is fixed to one area, the other two areas can be flexible and switched over as kids grow up and don't need to be under your feet the whole time - and as you live in it, you will figure out whether dining or sitting is better closer to the garden/light. I'd do a pro/cons list for each of the kitchen locations to help figure out what's best for you.

Alternative

Agree with Jonathan's lay out, you have walls for towers and wall units, with open plan designs you can be left with just base units due to the lack of walls, the option of a good sized island and the utility is moved into the garage which makes sense as its easier access when you come down the stairs. Dining and family zone is a flexable area that can easily change as you need it to and you still have a seperate reception room [lounge]