The 70-200 2.8.
I either shoot really wide, or really tight. I already have a 24-70, and that 24mm end gets used heavily.
Maybe get the 80-200/2.8 instead, since you do mention that you have an FM. If I was shooting a D700, instead of the D200, I would be using only D or regular AF lenses, in addition to my manual Nikkors. Reason being is that I have a few cameras that are incompatible with G lenses. Three that are completely incompatible, and one that's partially compatible. The F5, however, is fully compatible.
Granted, your mentioning that you use the 24-70 kinda nullifies that argument. At the same time, you can get an 80-200/2.8 regular AF or D version for less than $700. Half of what a 70-200/2.8 goes for on the used market.
Another option, if you can live without the extra stop of light, is the 70-210/4. Not the 4-5.6 version, but the straight 4. It, and the Series E 70-210 that it's based on, is a surprisingly decent lens. Yeah, the reviewers pan it from time to time, but I got good results out of the copies I had. One of which was a $18.00 lens (the E version 70-210).
If you go the 70-210 route, you can then grab a 250/5.6 Sonnar C as well without breaking the bank too much.
-J