Since you don't seem to shoot much in low light, either camera would work pretty well for you. I had the same dilemma and chose the D7100 because of its wider focus sensor spread and a couple of other features the D600 lacks. The D600 is pretty fabulous, though, and you may find that your 35mm DX lens works fine for you on that body. I put mine on a friend's D600 and found it quite usable, with only minor vignetting that could be fixed in post-processing. I don't think you can go wrong with either body.