My fav pic is no 1 as well...just so inviting!
Mum and Dad did a similar thing with their unit about 2 years ago. They built in book shelves around the gas fire, and incorporated a window seat..all in emporite. Looks fantastic!
I'd love to do something similar to the study, but making sure there is enough desk space for 2 monitors and a rather large printer..and 2 chairs! It would also work really well in the upstairs TV area, but I have found some Ikea open shelves that I will lay horizontally, put baskets in the four bottom shelves (for toys) and the TV ontop, so I'll use those for the time being.
http://www.ikea.com/au/en/catalog/products/50103086