The advantage of the full frame cameras over the D300 is better high ISO noise performance. If you are a landscape photographer you probably don't use high ISO's very much. So in that respect no advantage to the D700.
Now to your lenses. The wide angle lenses you have now are DX lenses. They will give you the same angle of view on both cameras. But here the D700 will need to be in DX crop mode and the view through the viewfinder will be smaller. Also in DX crop mode the resolution will be greater with the D300.
The telephoto zoom will work fine with both bodies but you'll be able to enlarge the photo from the D300 more because of the 1.5X crop factor.
The macro will be fine with both bodies.
Unless you shoot at higher ISO settings and get FX lenses I would say there is no advantage to getting the D700.