With good craft, the D700/D3/D3s are fine for both and for battery life in the field, the 3-series can't be beat.
Before that, the D2x made me a nice living off 30x20 landscape photos and both weddings and portraits.
Today, it's my D3s for portraits and social events and the D800 for field landscape and anything that's got to go super large, 50x30.
It's seldom the camera in the overall sceme that limits one, but the craft he creates from it.