As for a wide angle lens with a D700 take your pick and a lot will depend on your budget. There are the obvious Nikon candidates like the 24mm AF-D and the 20mm AF-D. Your 28mm will be pretty good stopped down to around f5.6 - f8. As you have the 28mm I would suggest looking for a used 20mm to give some real width. Also as it is wide you can comfortably buy a manual focus lens and be happy. The ultra wides like the 18mm MF still fetch high prices. If you have that kind of money burning a hole in your pocket go for the 20mm f1.8G AF-S. The newest Nikon 18-35G ED AF-S is getting some very good reviews.
There are some very good independent offerings from Tamron, Sigma and Tokina that sell quite cheap used. Wide angle zooms are a bit hit and miss in the older generation though some are very good if you keep to their sweet spot. The Tokina 19-35 (AF) is a very good lens at mid apertures and not too pricey used. I sadly sold mine to part fund my 85 f1.8G. For an ultra wide something like the Tamron 17mm may be worth a go.
You could always use the 28mm you have and stitch a couple of shots together in LR with the merge to pano feature
My suggestion would be to hunt down a 20mm AF-D Nikon first. If that does not work out then look at independent primes then zooms.
I like spending other people's money. It's contagious. I got it from my wife!