Regarding what #1 said about "I have been very satisfied with the reliability..." - i totally agree. It really saved my skin when i was hiking through Olympic National Park and got caught in a massive downpour for three hours. My gear was soaked but kept clicking. Just be a bit careful if you go with the Canon RF 14-35mm f/4L IS USM. It is way sharper than your kit lens, but you might want to consider that at 14mm it relies heavily on digital correction to fix vignette and distortion. I would suggest making sure your R6II has the latest firmware so it handles those profiles perfectly in-camera. Also, Glacier has killer reflections on the lakes, so maybe grab a Hoya 77mm Fusion One Next Circular Polarizer to cut the glare. It fits that lens perfectly and makes the alpine water look incredible. Better to be safe than sorry with those edges tho.

I have been very satisfied with the reliability of L glass for landscapes. You definitely need that weather sealing for Glacier.

• Canon RF 14-35mm f/4L IS USM: Sharpness is excellent and it fits your budget perfectly. Its my go-to for crisp edges.
• Canon RF 15-35mm f/2.8L IS USM: Works well but its heavier and usually over 1600 dollars. The 14-35mm is the safer bet for hiking. It wont fail you in the rain.

Unfortunately, rushing a purchase right before a trip is risky. Ive had issues with quality control where even expensive glass arrived with soft corners, which is a nightmare if you dont have time to swap it. To help narrow it down:

• Does that $1600 budget need to cover a weather-sealed filter too?
• How much weight are you actually willing to hike with?