You might want to add the Nikon 5100 to your list of cameras under consideration. It utilizes the same sensor as the D7000. Low light performance will be pretty much the same. (Which is pretty darned impressive) What you're not getting is the AF system of the D7000 which shouldn't impact your landscape photography as the benefit would primarily be seen in fast action photography. The D5100 body sells for around $700.
A good wide angle fast lens to consider is the 11-16mm F2.8 Tokina which sells for $625.00 or the 10-20mm F2.8 Sigma.
I've been a long time user of the Olympus E-30 + 12-60mm SWD lens for landscape/seascape photography and recently upgraded to the D7000 + 11-16mm Tokina. I find the D7000 and 11-16mm Tokina a very good upgrade.
I should point out that the reason I chose the D7000 was due to the more sophisticated AF system primarily, because I like to shoot wildlife and birds in flight.
Last edited by zig-123; Dec 29, 2011 at 6:03 AM.