Extension - interesting corner detail with bi-folding doors, really bringing the outside in. Great for entertaining! CLICK http://www.hollandgreen.co.uk/house_extensions#.U_L9sPldU7k to see if you could do something similar.
Single storey rear extension? this is a great example of how you can use your space. Seperate your kitchen area, but still keep it "open plan" for informal feeling with space for zoning of dining area. large velux windows and floor to ceiling concertina doors brings the outdoors in for those breezy summer days :) Simple. Love.