The D200 is an alright camera. However the D300 blows it out of the water.
Right now I am heavily pondering a used D700. I've had good luck with used equipment and saving a grand or so is vastly appealing. However my D300 is just working too well, however its age is showing. I checked and it just rolled over 70,000 shutters. That is starting to get a little high. I feel like transitioning to the D700 won't be too painful. Use the same battery and cards. Just need to ditch/put aside my 18-200 and get a 28-300 (or whatever FX version they have). I've been comparing the D700 to the D800, I'm not fully convinced that it is the right choice for me.