My first question would be how are you travelling? By car(own or rental), by train? The answer to that leads to convenience, cost and route choices. If a rental car, what about a drop off fee? If by train, what about a Swiss Rail Pass and if so, which type of pass?

For the places you mention, I would say that I like Geneva and do consider it worth a few nights provided you like what cities have to offer. I would definitely include a day trip to Montreux and a visit to Chateau Chillon either from Geneva or enroute to your next stop.

I also like Chamonix but it is of course in France and is a bit awkward as far as a route is concerned simply because it does require some backtracking no matter which way you go. So does Zermatt. Neither is a really big deal backtrack time wise but there may be alternatives that are on a more direct route to Como which appears to be your only must other than Geneva as your starting point. I would suggest you look at a road map or rail map as appropriate.

Some places like Zermatt, Interlaken, Lucerne, etc. are on most people's lists but often only because they happen to be the places they have heard of. I am not a Zermatt fan or an Interlaken fan at all. I find both far too touristy for my liking. As an avid hiker, I prefer smaller villages which may be in the same areas as the more popular tourist destinations but nowhere near as 'in your face'. For example, I prefer Tasch near Zermatt which also happens to be as far as you can go with a car if you are driving.

But if I were going from Geneva to Como and whether I side tripped to Chamonix and was travelling by car or train, I might decide to skip Zermatt altogether and instead stop in Leukerbad.
https://www.leukerbad.ch/adventures/summer/hiking/ Or in the Riederalp/Bettmeralp area where hiking alongside the Aletsch Glacier has to be one of the most spectacular places to hike anywhere.
https://www.aletscharena.ch/sports-s...resting-walks/ The problem is there are many, many places for hikers to base themselves and trying to suggest a 'best' is simply impossible. I could easily add another dozen stops for hiking between Geneva and Como.

One of my favourite spots near Como but still in Switzerland is Ascona. As a place to sit at an outdoor table and take in the passing parade, I prefer it over Como. Como is well known by tourists from everywhere, Ascona is well known primarily by European tourists. I consider Ascona touristy but not over-touristy. I'd say it was what Como was in the past and wishes it still was.
https://www.myswitzerland.com/en-ca/ascona.html
Who would think you can find palm trees in Switzerland!
Swiss with a twist: Fine wine, Michelin-star food and Lake Maggiore? Ascona looks and feels Italian - but this is 'hidden' Switzerland | Daily Mail Online
I might be temped to stay in Ascona and just drive across into Italy for the day of the wedding.