I got the D700 on Saturday and could not be happier. (I sold a D300 and some DX lenses to finance this.) While the D300 was really stellar, there are no regrets with the D700. It feels so good to have the lenses working like they were designed to again -- and call high-iso performance "one stop better" if you want -- shooting this camera in low light feels like it opens new worlds of opportunities.
The only drawback is the purchase cleaned me out of two DX lenses that I really enjoyed owning. But I was pleasantly surprised with how my trusty old 28-105 performs on the D700. (I can hear the groans from the crowd for putting that humble lens on the D700 instead of something like the 24-70, but you should try it before you knock it. That lens has long been regarded as a "Decent" consumer lens, and it delivers exceptional images on the D700. Really.)
I will miss the convenience of the 18-200, but I will enjoy owning an 85 1.4 and other leganday fast primes that I'm heading toward. Those primes will supplement the 28-105 -- which will serve as a compact walk-about lens for now.