EF-S 10-22mm f3.5-4.5 USM At around $650
Seriously any lens can be a landscape lens. It depends on what you are 'really' after. I have used my 600mm f4.5 as a landscape lens. I have used my 8mm f4 as a landscape lens.
Decide what you want your shots to be and than find the equipment that will get it for you. But the 10-22mm is a fine place to start.
This was done using a 15mm f4
This was done using a 10mm f4.
I am really into shooting landscapes and I want to know what would be the best landscape lens option available from either Canon or other makers. My budget is anything under $1,000. I am looking for a lens that will last me a long time. Any ideas?
If you're not contemplating going full-frame anytime soon, get the EF-S 17-55mm f/2.8. Otherwise, get an EF lens, so it won't go obsolete on you. The EF 24-105mm f/4 is a bit long for a 7D (I seldom used mine until I bought a 5D3), but is a very versatile outdoor lens on a FF camera. Some claim it can now be had more cheaply than the 17-55.
With a full-frame the new EF 16-35mm f/4L would be a great lens. When you shoot landscapes you tend to want to maximize the depth of field ... so while there's a 16-35mm f/2.8L you probably wont need f/2.8 (at least not for landscape shots.)
Tilt-shift lenses are ideal for landscape & panoramic landscapes but they are expensive. When you use them for panoramics they do create non-distorted images (it's not like stitching images from regular lenses).
There's a good Tokina lens, the 11-16mm f/2.8, which is available for your Canon. I have a Tokina 17-35 f/4 for my 5DII and am impressed with its performance. The price is also attractive, as is the three year warranty.
If you're planning to go full-frame you may want to consider the EF 17-40mm f/4L.
A 16mm lens on a full-frame body provides roughly the same angle of view as a 10mm lens on an APS-C crop frame body. While the 17-40 doesn't quite get you to 16mm... the 16-35mm lenses are about $1700 for the f/2.8 version and about $1200 for the f/4 version. But the 17-40 is just slightly over $800.
Full-frame bodies cannot use Canon "EF-S" lenses (such as the EF-S 10-22mm). Those lenses only work with EOS bodies that use APS-C crop-frame sensor cameras.
I think the 10-22 is way too limited for a general purpose landscape lens. I would recommend the 15-85, priced at about 600-700, I think. This range is analogous to the FF 24-105. I would add the 10-22 as my next lens, but it just depends on what you're shooting, as well as your shooting style.