You've got some great advice so far. Let me add my voice to those who've said
(1) the 14-24 is not IMO the best choice for landscapes. Nikkor 16-35 f/4 VR or Tokina 17-35 f/4 are more practical focal lengths for landscape, and they take filters. Or a set of primes. Also the very inexpensive 50mm f/1.8D makes a good complement to these, and for landscape work stopped down to f/5.6 or smaller it's indistinguishable from it's more expensive siblings.
(2) You can combine your street goal with a medium macro lens, like Nikkor 105/2.8, Tamron 90/2.8 or Sigma 70/2.8 which are all excellent. You'll probably want a longer macro lens later but this gets you started.
(3) Panoramas! Start here and prepare to spend the rest of your money: www.reallyrightstuff.com (my wife would probably prefer to find a playboy tucked under my mattress than the RRS catalog). They have some great pano tutorials there as well. They sell leveling bases compatible with your Gitzo Series-3 Systematic, but like Eric says, this is basically a time-saver compared to leveling by adjusting the legs. You can use a leveling base combined with a ballhead as your panning base, or get their PCL and use your ballhead as the leveling base. None of that probably makes sense but read the RRS tutorials then it will. For panos I strongly prefer RRS clamps/rails/brackets because they all have nodal index marks and make setup for panos a breeze.