First Time to Europe

My advice is always to find the best transatlantic flight. Best can mean shortest, cheapest, most comfortable, paid for with miles, whatever it means to you. Get over the water. For most people, the best flight is usually direct to London, Paris, Amsterdam or somewhere in Germany. Don't feel like you have to fly home from the same airport, of course. And be open to adding some time in another country (preferably one that is less expensive if cost is what's limiting your trip to two week) on the way in or out. Distances are short in Europe, and train travel is inexpensive if you plan ahead. You won't get a lot of flight options until the spring, so in the meantime...
Most of the folks on the Forum will say that planning is the best part, which is why we spend time helping other people plan their vacations. The first step in planning is imagining. Start reading the books, watching the movies and YouTube videos, etc., with your wife and talk about what you want the trip to be like.
It might be easiest to start with Paris because it's one city with LOTS to see. And there are lots and lots of books and movies set in Paris.
Here is Rick's information re: Paris:
https://www.ricksteves.com/europe/france/paris
Rick's information on Switzerland:
https://www.ricksteves.com/europe/switzerland
Keep in mind that you won't be graded on your itinerary, and you're not required to see all the things. Nor are you required to be joined at the hip every moment of the trip. For example, if one of you wants to read all the placards in the museum, the other one needs to go and do something else (like sit outside a cafe and drink coffee/wine). Indulge your common AND separate interests is what I'm saying.
To stay organized, I use a spreadsheet with columns for date, destination and transport info (i.e., train to Paris, departs at 10am, arrives at 4pm), accommodation, activities and food. This document ultimately becomes a very detailed itinerary, which I share with my travel partner and someone back home.
Every time you see or read about something you want to experience, put it in the spreadsheet in the section for the city/town/region that is closest. This will help you determine how much time you need at each destination. Add in rest days and/or thermal spa "recovery" days. Take into consideration the altitude, especially if you are planning to go to Switzerland first. Jet lag and altitude sickness are a terrible combination.
Here is Rick's advice on trip planning:
https://www.ricksteves.com/travel-tips/trip-planning
Finally, if you can give yourself more than 2 weeks, do. You won't regret it.

Start in Switzerland, as lifts will be closing down in October. September is a great month to be in the Alps. Have a great trip!

Since it's your first time, I would recommend staying in one place the first 3-4 days, then as you get your European footing, you can then branch out to another city or two.
We are the same, we like doing our own thing but we always follow along on the walking tours from the Rick Steve's guide booksT, they really help you get to know the area you are in and give you an idea where most key sites are so you can go back during the week in more depth.

Itinerary thoughts:
Land in Zurich and head to Lucerne for 3 days,
head to Murren to see the mountains and stay uptop the mountains - 3 days
head to Bern for 2 days
head to Paris

If this is your first time in Europe, and perhaps even your first time outside of the US,
while I understand your desire to avoid tours, you may want to consider how prepared
you can be for dealing with situations that require you to be creative, or use technology,
or handle something you're unprepared for.

For instance, if you have no idea of what you're going to do today, are you both just
going to look at each other, or is one of you willing to dive in? Will you have enough
information at hand (or know how to find things out) to make the most of your time?
If you are lost, can you use your phone nav to figure out where to go? Do you have a
phone plan that works overseas? Are you versed enough with the internet to find a bus
schedule if you need to? How will you handle paying for things?

A tour, for the first time overseas, does (at a cost) help you see what you might have to
deal with if you take more trips and want to do it on your own.

In my personal travel, I've never done a tour, but I traveled in Europe a lot for business,
so my experience level was decent enough to learn how to figure things out. No offense,
but if you are in your mid-70's, and your tech expertise level is not that high, working on it
before your trip will pay dividends. Not every moment of every day, but at that once or
twice during the trip when you are stuck and have to figure it out.

A compromise would be to do a My Way tour, which includes transportation, lodging and advice from the tour manager. The 12-day Alpine Europe is the only one that includes Switzerland:
https://www.ricksteves.com/tours/europe/my-way-alpine

I recommend that you read the Rick Steves Switzerland book. It’s packed with information that will help you, as a first timer, plan your trip. Read through it and decide if independent travel is for you. It really isn’t that hard.

If you think independent travel will work for you, then buy Rick’s book for Paris. Go to the shop — then the guidebook section and read about which book is right for you. There are several books that cover Paris.

This is your trip, so you should do what you want, Combining Switzerland with Paris is a little awkward because of the distance to get from Switzerland to Paris. You could fly or take the train, but it would take a good part of the day. With limited time, only you can judge if you want to spend much of a day in transit to add Paris to your trip. But if Switzerland and Paris are both at the top of your wish list, go for it!

Since this is your first time to Europe, I suggest you start by getting a copy of Europe Through the Back Door by Rick Steves. It's a good primer for first time travelers to Europe. It's also available from Amazon, your local bookstore as well as an ebook.

From there, it's time to figure out exactly where you want to go and what you want to do. Place specific uidebooks will be helpful but don't rely on just one. It might not cover areas you wish to visit.

You could also visit tourism websites for Switzerland, Paris and the local areas. Almost anywhere that wants tourists these days has a tourism website. (Just make sure it's the official site.)

Once you start doing that, you'll have questions. That's when its time to come back here and ask.

In addition to the other posts. Switzerland is a good place for your first trip to Europe. If you do some research/homework before traveling it will make the trip smoother. There are several online information sites to plan and navigate your trip like myswissalps.com. These sites have posted several YouTube videos and offer personal help with trip planning and itineraries
thetravelingswiss.com/
switzerlandinsider.com/
aplinsinthealps.com/