What lenses do you use?
Buying a body with more megapixels will never give results as good and investing in more suitable lenses. For landscapes, you're much better off just taking time and improving your technique to get the composition you want as you shoot, cropping will never produce images as nice as a well composed shot to start with.
If you do just want to crop instead, the 550D or 60D are probably your best options with canon's most recent 18mp sensor. But really, I would be looking at lenses in your position, not a new body![]()