Sorry Dennis, I only considered your--what I thought was overarching goal. For that I would recommend the D7000.
I was thinking that a man with both a D700 & a D800 wouldn't have any quibbles about a few hundred dollars. Just sayin...
If you are used to controls on the D300, be aware that while many of the controls are similar, they are not the same on the D7000. That might be confusing. I had a steep learning curve for the D7000. There is much that I could say good about the D300's controls over the D7000.
One "feature" that I like is the DOF button on the D300. It makes a click that some would think is the shutter. When in groups where you are shooting candids, it seems to put the group at ease as you click away on the DOF button. Learned that trick at a RMSP session. I also like to have the ISO on a dedicated, labeled button. Some controls are exactly opposite on these two bodies, like the Fn & DOF buttons. If that confuses you, you can change them in the menus on the D7000.
If you need a grip, and you already have the one for the D300, then that would be an additional monetary consideration. Do you really need one for a transitional/backup camera? Batteries for the D300 are the same as the D700, the ones for the D800 matches those for the D7000. So that shouldn't be a consideration.
To get a real good handle on the comparison, why don't I swap you a D300 & a D7000 for your D700 for about a month. I'd even throw in a D80 & a Canon A-1 complete with powerwinder, flash, and 18-105mm lens with closeup feature. I know that I am being extraordinarily generous, but you are a fellow Nikonian, correct?