Just to add, the 50/1.4 Nikon or Sigma variant is a great option, but remember, wide-open at 1.4, the depth of field is very shallow. So for instance, in a close-up portrait, the eyes might be in focus, but the nose and ears won't be. This is a great effect, but just know that there is always a trade off when shooting at large apertures.
The original Tamron 17-50/2.8 is a phenomenal lens (the one without the built-in motor). I've had mine since 2007, and it works like a charm on the D7000.
It may make more sense than a single focal length (30 or 50) at this stage.