im not too familiar with nikons, but don't they have like a 12-24 or 14-24(28?) lens as well? i would find that to be a good intermediate uwa lens. i've done a 24-70 and 24-105 before on a crop and i just felt it a bit too tight, whereas the 10-20 sort of lacked in range for me, hence i'm thinking of the 14-24 or 12-24
