I went through the same process. I was generally satisfied with my D3, but wanted the better low light autofocus the D4 offered. I thought it would be hard for me to put the D3 up for sale since it had been such a good body for me. Once my D4 arrived it was a different story. The D4 was so superior I had no problem at all listing the D3. I believe you will be very pleased with your decision.
Occasionally I take a shot where I could use the resolution of the D800. But my D700 or D4 have enough most of the time. I'll get a D800 someday, but I am in no hurry.