So your actual question is - "Should I buy the D700 or the D800?" And in the subtext of that - "Is 36MP too much to handle?" Please let us know if that's not the case.
Assuming your profile is up-to-date, you should be okay jumping to the D700. You've got the right lenses to take advantage of FX. The D800 is another league entirely - not because it's new, but because significant moves uptier in resolving power tend to reveal things - chiefly among them are the photographer's handling habits and just how good their lens inventory really is. Sometimes the results are good, sometimes bad. It doesn't mean you can't move up - the only limiting factors there are availablility and money, but from a practical perspective - will you gain anything from it? Conversely, what is stopping you now with your D200 that you won't or can't gain with a D700? Or even a D800?