My favourite Teletubbies
sketch involved noisy walking!
Back on the subject of this thread, it's a mistake to assume that landscapes should always have huge depth of field. As autumn approaches here in the temperate latitudes of the Northern Hemisphere members may enjoy the Canon Digital Learning Center article Quick Tip: Fall Foliage Photography (2008)
. One image, from several candidates, in that article makes my point:
That's not to say that most landscape shots don't generally work best with large depth of field but then just because a 50mm lens can reach f/1.4 that doesn't mean it should always, or even often, be used at that aperture. But if such a lens is in budget then it certainly offers extra capability and could be a valid choice as it can also be used as a portrait lens on a cropped sensor camera.
That said, my personal take on this is that if the emphasis is totally on landscapes/sunsets then a better investment, if one isn't already in one's possession, might be a tripod as that will allow longer exposure times allowing the shot to be captured without either unwanted shallow DoF or high ISO noise.