Don't get hung up on you memory cards. They are an accessory and getting cheaper. Your D70 uses SD cards and the D300 and D700 CF. Of course a D300s uses both.
Video is there, whether you want it or not. I have 3 DSLR's with video capability and I have yet to use it on any of them. I bought these cameras for their other capabilities.
The D7100 has 51 focus points, not 39, as the D7000 had. It will give you more pixels on the subject than a D700, and you can use your existing DX lenses. The dynamic range improvements over the D300 and D700 are amazing.
You'll pay as much or more for a used D700 than you will for a new D7100.