Love the floor, reflections are always good :D

I hope its ok, but if i could make some suggestions if you are still working on the scene. The background seems a bit stretch so i tried to replace it with a more detailed sky map.

Also a good idea i think, would be to break the straight line outside the door, the area which i marked with red. Meaning throw in some benches maybe some flowers etc. Just so you don't get a straight line between the sky and the floor. Think that could really spice it up and you would get a nice feeling of something happening inside but also outside.

The map i used for the sky I just added in PS, so it would look better when rendered i think and i added some noise etc to match your render. But its actually part of a high quality HDRI package with 10 different sky maps, that you can download for free from here, if you need some: http://www.viz-people.com/portfolio/free-hdri-maps/

But think you can get a really nice image out of it.