When you say you want to print 24" wide, do you mean you want to print 16x24", or 24x36"? 12mp isn't going to cut it for 24x36" prints IMHO, not if you really care about fine details and print quality. I would plan on stitching if such large prints are your goal. 12mp can do pretty nice 16x24" prints if you use good glass and technique.
As for which lens, there are lots of excellent choices depending on what focal length you want to shoot most, what your budget is, whether you're willing to use manual focus primes. For sheer optical quality I'd say some of the best lenses would include:
Nikkor 14-24
Nikkor 24-70 (great from 30-60mm, still quite good outside of that range)
Any of the Nikkor PC-E lenses
Nikkor 60mm AF-S macro
Nikkor 105mm AF-S VR macro
Zeiss 35mm f/2
Zeiss 100mm f/2
Sigma 150mm Macro
among others.