Hi there, how cool that your daughter works at CERN. A visit there should be very interesting!
Since Montreux is not on your list, I don’t see why you would spend more time in the Geneva/Montreux area as some have suggested above. You already have an extensive wish list, why add on things you have not expressed an interest in seeing?
It is perfectly fine to arrive in the morning, head to CERN (25 min from the airport) and then travel further that afternoon.
You can use the SBB app or website to see travel times.
It looks like you are aiming for more intermediate hikes. Each one you mention will have multiple other hikes in the area. Here is the website for Grimselwelt, where the Trift bridge is:
https://www.grimselwelt.ch/en/experiences/outdoors/
And you could add fun things like the Gelmerbahn
https://www.grimselwelt.ch/en/railways/gelmerbahn/
Often one hike in particular becomes well known, but check out the websites for any of the hikes on your list and you will see just how rich each area is. Exploring one (or two) areas more will be far better than traveling back and forth across the country.
I really like the Basel zoo, have not been to the one in Zurich for a very long time, so can’t directly compare them. Just because someone else would not put it on their list of things to do does not mean you shouldn’t. This is your holiday and it’s great that you are taking all of family members desires into consideration.