I currently use both the D7100 and D700 and shoot 95% out doors.
D7100 is great in good light and has better DR than D700 at base ISO imo, however living in the UK means I rarely shoot at base ISO. The highest I'll go with the D7100 is ISO 400 where as with the D700 I'll be prepared to go to ISO 1600-2000 if needs must. D7100 sharpness drops considerably beyond ISO 400 - it's fairly noticeable if you like large pics (I do), but if not then I'm sure you can contently go up to ISO 800.
D700 has better AF than D7100 - rarely hunts in poor light and gives a far better hit rate in continuous focus release mode in any given light. If you'll be shooting indoors, in poor light or without flash then D700 is definitely the way to go as it'll produce more keepers. If you want to get into wedding photography then D700 is the better option imo. My only gripes with D700 are it's clunky loud shutter and it could do with a bit more resolution.
I prefer the handling/weight of the D7100 and in good light it produces some fantastic shots. I have a love/hate relationship with D7100… and it's more hate than love! For low light or even in overcast conditions shooting I won't touch the D7100.