The Tamron 17-55 f2.8 (I got that right, right?) will probably be a good lens for you. You don't need something super wide for landscapes, trust me, it makes everything look less impressive than it is. If I'm shooting landscapes, I would rather shoot a mountain range from 20 miles away with a tele, or more standard focal length lens than right underneath them with a superwide.
If you're looking for that super wide angle look for skiing, however, I'll for sure put in a plug for the Tokina 11-16 f2.8. It's a great lens, but it starts super wide and stays super wide, 16mm isn't a HUGE change from 11.