My experience was that when I moved from the D2x (DX) to the D700 (FX) my photography took off. I only later acquired a D300 (DX) camera. I would highly recommend a D700 and one new lens, the 24-120 f/4 VR, to start with. You can later add a true wide angle lens like the 16-35 f/4 or the 14-24 f/2.8. Then the 70-200 f/2.8 and the 105 f/2.8 macro.
My current camera lineup is the D2h, D2x, D300, D200, D700, D3s and I have over 40 Nikon lenses.