Paul, you have good points and I promoted a misunderstanding. To elaborate:
Quote: "The 24-70 2.8 would cover about 90% of what i shoot, for the rest I think i would carry a small superzoom so as to have less gear, or just the zoom lens for those occasions or a tele converter
Its interesting that there is a Tamron 28-75mm f/2.8 Di III RXD and owners are saying they sell the Sony glass once they have this and its a 1/3 of the price with 99% equal sharpness, but a lot less weight. Any opinion on that?"
The Sony 24-70mm is recommended over the Tamron 28-75mm for your application based on 2 points:
1) 24mm is around 12 percent more FOV compared to 28mm. For vista and panoramic images this is a non-trivial improvement in single-shot performance.
2) The Tamron 28-75mm f/2.8 Di III RXD is so new that durability is fairly unknown. I recently upgraded from an (admittedly ancient) EOS 28-80mm, f2.8-4L USM to a Tamron SP 24-70mm, f2.8 Di VC USD, primarily to benefit from the extra FOV. It also provides a very usable image stabilization which is appreciated in indoor and low-light situations (important to Canon users since the camera body doesn't help with stabilization). The old Canon lens is a significantly more durable construction, and both lenses suffer similarly with mis-focus at close range, but otherwise the Tamron is a great performer.
For your sort of harsh environments I believe that the seals and construction of the Sony lens will provide a better experience overall, and from looking at your Internet published images I also believe that you will appreciate the wider FOV. It would be a good idea to review your EXIF for your wide images to see how often you bump up against the widest FOV limit.
Quote: As for waterproof I use waterproof bags over plastic because plastic tends to sweat and not breath enough. They actually sell on ein Wally World for about $8 which is DSLR sized
We are in agreement in a wet environment concerning plastic bags and storage of wet equipment.
In a dry but dusty environment, cheap polyethylene bags provide additional protection against dust migration, which is important when you have to change lenses more often. When they do get overly/overtly dirty just throw it away and replace. (Generally, just demote them back to a garbage/refuse bag.)
In a wet, snowing or blowing snow environment a plastic bag provides a simple and effective primary watershed just by punching, poking or cutting a bottom corner through which you push a bit of the lens.
Keeping the equipment clean and dry in the first case is just easier with prudent use of plastic bags. I keep a few with me at all times. (Boy Scout motto here)