A design concept for a roof garden on a commercial office

We require a garden concept for a large roof area on a commercial office, i have attached a overhead google view of the roof for its shape, basicly a square and the client has sent a picture of something he likes (mars slough 1) to be some kind of element also a rough sketch of the roof with a very rough survey drawing with basic concept which is not liked that much but we want to combine hardwood decking in areas with somthing like the seating idea around the edges and centre with planting boxes around with a nice slatted fencing around all the garden perimeter as it has to block out the ugly surrounding. we are looking for a very slick either very realistic look or a very high end sketch look. size 26.5 x 19.5