Upstairs Built In's

I am struggling at the moment to get my head around my upstairs living area. I have a library and a sitting room - The library is easy - Shelves however the sitting room will include a computer / home office, kitchenette and a small and cosy TV room. I would also love to incorporate a window seat if possible. I love the idea of window seats and am dying to find a place to stick one!

I know I want built in's for the study, kitchenette and the library and I want them all to match beautifully but how the will sit, what layout, colour and finishes I just cant seem to get sorted.

This is sort of what I was thinking - perhaps by putting it down on my blog I will clarify what I am after.