Upload & Sell: On
+1 on everything said about your pictures!! You are an artist!
In reading the thread I was about to add that if I were you, seeing as how you don't like the D600 (which I love), I would stay with the D700. But after seeing your pictures, I have had to re-think my position. With your "eye" I would consider switching to the D800 - but to be frank with you, I would try my hardest to get the D800E. You are good - and your prints should be hanging on people's walls - so you should have the highest quality IQ possible - and that today is the D800E (along with the D3s and D4). However, with the D800(E), as others have pointed out, there is a higher cost that comes along with the D800 - high quality (read expensive) lenses/filters, high speed computer, high capacity disk drive(s), longer PP time - at a minimum - I had the D800, I know!! The D7100 is a very good, high quality camera (as someone suggested) but with your style of wide angle, it is counter productive.
If you can swing the change to the D800(E), I would switch and keep your current 14mm. If you can not make that entire commitment, then I would stay with the D700 and add a lens. However, since you have a good 14mm lens I would not switch to the zoom 14-24 - not that significant of an upgrade when cost is factored in. I would consider adding an additional, high quality, FL lens (Zeiss 28, 35 or Sigma 35 1.4). I think you would be better served by the later and waiting on the next Nikon upgrade (or winning the lottery and getting the D3s/D4). With the additional lens you will have added additional latitude to your work, and already have another high quality lens when you camera upgrade later.
Bless you - and the work that you do!