So I am going out to Banff / Jasper next week and I plan on getting the 6D beforehand. I'd like to pick up a lens or lenses for landscapes. Right now I am looking at the Canon 16-35mm f/4 L IS USM for $999, unless I can get two very sharp but not-so-fast wide angle prime lenses for around the same money. What is the best way to go? Any specific lenses you recommend?