Can't really give any true C&C on people photography, as posed people photography is so totally not my realm, but I am impressed with the sharpness of these photos! That much is true.
Gotta give people a chance. You posted these in the middle of the night and then seem disappointed when no one has replied in 2 hours.
1. Looks nice although the flower is a bit overpowering and distracts from her
2. Seems a bit washed out.
3. Could use more contrast. His shirt is blending in to the fountain. If it wasn't a plaid he would just be a floating head.
Things I did notice though, in 1 it looks to me like she is squinting a little too much because of the intensity of the natural light, maybe drop the saturation of the hedge behind her a touch, 2 is a little better. 3 feels like it needs some straightening.
For the first two:
Raccoon eyes. Consider adding fill flash or using a reflector to remove.
The bits of sky is not attractive. It looks as if you have plenty of background where you could've elimated it from the frame. I carry a two-step ladder with me. This would allow you to raise your camera position slightly.
The WB is different between the two. With both shots having the same lighting, they should be the same. Easy fix in post.
In #3 she was leaning a little bit, and I think that's why it looks a little tilted. But I could be wrong. These photos have been played with in lightroom, so they are all different. I guess I should have made all the adjustments the same. Next time I'll use a reflector, since I haven't gotten a flash yet (plan on getting a SB-600 soon)..But for now it's natural light for me. In #3 I liked it a lot because I caught them acting natural. It's really hard to get people to be loose and act normal! As for the eye squinting..I noticed in a lot of pictures her doing it, and I think it's just her. Like a "smile with your eyes" type of thing. It was overcast when I went and did these pictures.
Thanks for the C&C though!
Oh and yes! I LOVE the D700. Definitely worth the money.
I think, and I might be wrong, but the images might be a little small to tell a huge difference? Also if I'm not mistaken, the camera is a full frame right? If so, then you should really some landscape photos and post them in large size.