You should look at the Nikkor 24-70 mm f/2.8 ED. It's performance is truly excellent although at the wide end, perhaps 24-28mm, it is not as stellar as at other focal lengths (still quite good, though). At 70 mm you have a portrait lens, and the focal length range encompasses many landscape needs. It costs about $2k, I think. It is not compact or light, I'll tell you that!