TL;DR: Grab the Canon RF 14-35mm f/4L IS USM! It is absolutely perfect for hiking and real estate, saves you tons of money, and stays light in your pack. Honestly, if you arent shooting stars, you dont need that heavy f/2.8 glass. Since you are doing landscapes and real estate, you will probably be stopped down to f/8 or f/11 most of the time to get everything in focus anyway. I have used this lens for a ton of interior shots and even though people complain about the software correction, the final images are fantastic! The camera profile fixes the distortion so well you wont even notice it in the final JPEGs or in Lightroom. The weight is the biggest factor here. Hiking in the PNW with a heavy setup is exhausting, and the 14-35mm is so much more compact than the Canon RF 15-35mm f/2.8L IS USM. It fits 77mm filters too, which is likely what you already have in your bag. The edge-to-edge sharpness on the R6II is amazing with this lens, seriously. I love it! Dont worry about the software correction stigma... its just how modern lenses are designed to stay small. You will save a ton of cash and your neck will thank you after five miles on the trail. Its a total win-win!

I stumbled on this thread and had to chime in because I've been using that exact setup for a year now. Like someone mentioned, the Canon RF 14-35mm f/4L IS USM is really the way to go for the specific stuff you're doing. I was also worried about the software correction stuff at first, especially for straight lines in architecture, but honestly its just how mirrorless glass is built now. The R6 II handles it perfectly in-camera for JPEGs and Lightroom has the profile ready to go for RAW files. I'm super satisfied with how sharp it stays in the corners even after the correction. The weight difference is the real clincher though. Lugging the Canon RF 15-35mm f/2.8L IS USM on a five mile hike in the PNW sounds like a nightmare for your neck. Plus, you mentioned filters... the 14-35 uses 77mm threads which is the standard for most pro glass, whereas the 2.8 version forces you into 82mm territory. If you've already got a kit of filters, staying with 77mm is gonna save you a fortune. For real estate, you're usually on a tripod at f/8 anyway, so that extra stop of light from the 2.8 is just wasted money and weight. If you really find yourself needing a tiny bit more reach or a faster prime later, you could always toss the Canon RF 16mm f/2.8 STM in your bag as a backup since it weighs basically nothing, but the zoom will do 95% of your heavy lifting. It's a killer combo for the PNW trails and your clients wont even know the difference.

> then people say the 15-35 is just a brick to carry on a five mile hike. I'm so satisfied with the lighter lens choice. Lugged a heavy f/2.8 setup through the cascades once and honestly, it ruined the trip. Just a warning... dont fall for the pro gear trap if youre hiking. The f/4 glass is a total lifesaver and for real estate, youre on a tripod anyway, so that extra weight is basically useless. My back is much happier now.