I fell in love with the Nikon 12-24.. great super wide lens. However I don't do too many landscape shots so I have a hard time trying to justify adding to my stable.
I would look into Tokina 12-24 F4 or 11-16 F2.8 for a more inexpensive alternative.
Don't think of your wide angle lens as a landscape lens......
Check out the Sigma 10-20mm as well, love mine on my D5100
Heres some of my photos using it.
https://www.flickr.com/photos/77016346@N03/sets/72157636079630715/
I am such an embarrassment!Wait....did you just post for a CANON? The shame!
The tokina lenses are very nice for the price.