Help! I don't know how to design travel in Switzerland

The Swiss rail system is the gold standard. They run perfectly on time, are very comfortable, and can get you about anywhere. Also, the train stations are usually in the center of the old towns.
The quick and easy would be 4-5 days in the Berner Oberland, ( Wengen or Murren,) and then the rest of the days in charming Lucerne. No one is ever ready to leave the Berner Oberland. Watch some u- tube videos , join some Swiss Facebook groups, read the related sections here. Look at the RS tour route. Check out the suggested routes in the RS Guides books.
You will probably have difficulties finding lodging at this late date, so that may influence your itinerary.
Enjoy my favorite country!

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From Zürich Flughafen (Zurich’s airport train station) take a direct train to Fribourg/Freiburg: https://www.sbb.ch/en (2h). The direct trains are 1h apart leaving at 8:08a, 9:08a, etc.
Spend five nights in the Lauterbrunnen Valley. You’ll spend a good portion of the day traveling to and from there but it’s worth it. You need to decide where you want to sleep and reserve a place ASAP: https://www.ricksteves.com/europe/switzerland/lauterbrunnen-valley then click on the + on the right of At a Glance.
To get from Munich to Vienna see: https://int.bahn.de/en.

I'm happy to help plan your itinerary with you -- I like to think that I'm very good at it! What are you guys into? Hiking? Adventure sports? Museums? Why are you set on Iseltwald? Are you a beach person or mountain person?

Feel free to post here or DM me.

Best,
Dave

From Zurich airport you will likely have to change trains at Zurich Hauptbahnhof and maybe Basel, but the journey is quick and easy.

Coming back to Switzerland, you will aim for Bern, gateway tothe Berner Oberland, To reach Iseltwald, you need to take the train to Interlaken Ost, and then a bus to Iseltwald.

If you can say where else you want to visit, people here, such as David from Baltimore, above, can help you figure out the best base village, and the train routes. The Swiss train system is very reliable and easy to use (even for those of use who grew up in Southern California with no public transportation.).

@marypat and bloofan: just want to point out that Freiburg/Fribourg is a Swiss city near Bern, not the city in Germany, which is Freiburg im Breisgau. There are no direct connections from Zurich airport to Freiburg in Germany, you have to change in Basel. It will still only take a little over 2 hours. Easy to get the two confused, so make sure you search for Freiburg (Breisgau) Hbf if you want to visit the German city.

will it just be the two of you on this trip? No kiddoes or parents? Any mobility issues?

sorry for so many questions - anybody helping you with this will need these answers.

About the Iseltwald - is that just for one day/night, or do you intend that to be a home base for several nights?

With both of you working 80 hour weeks now, perhaps a guided or escorted tour may fit the bill for you. There are so many things you feel you need to figure out you would benefit greatly from third party planning. Otherwise what may your 80 hours turn into with all the research you feel you need?