Eurail pass or Swiss pass?

I would not mess with a Eurail Pass. How long will you be Zermatt before you get on the Glacier Express? How long will you be in Chur or St Moritz before getting on the Bernina Express?

Price out the cost of individual tickets. Then compare the cost to the passes. It may be less expensive to buy individual tickets.

Going from the Netherlands to Zermatt is a very long rail journey - but then, even if you fly, you are left with a 3 hour+ train ride to reach Zermatt.
There is a direct train from Amsterdam to Basel Hbf, best bought on Deutsche Bahn (German railways).
For the rest, you can indeed buy a half fare card and purchase your tickets on SBB (Swiss Federal railways). Or a 3-day flex Swiss Travel pass might be slightly cheaper; you have to do the math!

How are the other 3 getting to the meeting point and from the leaving point to the next place?

Will they go with you as far as Tirano, the end point of the Bernina Express, and you go and they ...? Will they return to Chur, rent a car in Italy or take a bus to Lugano?

Does your party want to take the named tourist trains or save money and have more flexibility but no super-tourist pizazz on the more frequent, same places, same views, same speed just about local trains? That's a valid question both for the Glacier Express and the Bernina Express routes.

Are you money conscious Second Classers or prestige and perks conscious First Classers? I mean all of your travelling group. Sorry to put it that way but I don't know an easier description. I'm not shaming you either way - heck, I don't even know you - but again it is an important question to help you make these decisions. There is no wrong answer.

Part of why you're "struggling" is that train passes aren't necessarily the best deal for your itinerary. This is true for a lot of people these days. Eurail did such a good job of selling the concept that even people who've never been to Europe are SURE that a pass the best way to go, or is even necessary. Neither is true.

For Switzerland, some form of pass is often (again, not always) a good deal. For other trains, passes are rarely a better deal than advance purchase tickets. As long as you can accept non-refundable and non-exchangeable tickets (or tickets that have significant restrictions on these actions), you can save a fortune.

Before getting any pass, read this summary from rail guru The Man In Seat 61, and make sure you understand all his points:

https://www.seat61.com/how-to-use-a-eurail-pass.htm#railpass-or-point-to-point-tickets

We have used the Eurail passes in the past with no problems and used them on the latest trip but I would NEVER use them again, ever. We, and many other people, had bugs with their app and had many struggles getting it to work. The worst part of that is they have NO real time help in Europe while you are on the ground, no phone number—only an email system that continually told us and others that they wouldn’t be able to respond for a week due to backlog on this very issue! The only way we found a workaround was hours spent on their forum where someone else had found a workaround for the bug on their app. Hours of frustration. I will never use them again.

I will echo Harold's post , no point in repeating any of it . As an example - My upcoming trip ( Autumn 2022 - 11 weeks ) is structured thus - All point to point tickets , purchased in advance at lowest prices , with the exception of a 15 day Swiss Travel Pass , covering two weeks in Switzerland .

The Op has not responded to any requests for more detailed trip info to get them a good answer, so I would not waste any more time on them until they do.

Thank you all for your thoughtful replies. I've read them but not been on the forum for a few days.
We have a very limited time for the Switzerland portion of our trip. We'll meet friends in Zermatt, take the Glacier Express the next day, and the day after that we'll take the Bernina Express to Tirano and then travel to Florence. My party will be in Switzerland for 3 nights.
Looks like there's no glaringly simple answer here- I'll do the math and go from there.

Ok, so it is much clearer now. The easy option is a 3-day Swiss Travel pass but for 232.- excluding reservation fees it is not worth it, as I assume you will not have time for any mountain excursions in Zermatt (and even then, you only get discounts there, they're not fully covered).

You should buy 2 "Saver Day Passes" for the day when you go to Zermatt and the day when you go to St Moritz, and a simple point-to-point ticket for St Moritz to Tirano.

Let's break it down (all figures in CHF). Saver Day Pass should be bought 60 days before your journey for best fares, it would then cost 54.- on a weekday and I think 70.- on a weekend. It is still MUCH cheaper than the point-to-point tickets from Basel to Zermatt and especially from Zermatt to St Moritz (although you still need to pay 39.- for the Glacier Express reservation fee)
St Moritz to Tirano costs about 30.- plus whatever the supplement is for the Bernina Express, which you do not have to take - a regular train will do - so no need for a pass.
All of the above can be bought on the SBB Swiss Railways website.

With this scenario, you could do the whole journey for about 200.- or less, including the reservation fee for the Glacier Express.

Just a note…the Swiss Travel Pass will be 25% off starting Nov 11. So I read.

Sean , where did you see this ? Looking at the SBB site , I seen no such reduction on the price and coverage of a Swiss Travel Pass .https://www.sbb.ch/en/leisure-holidays/travel-in-switzerland/international-guests/swiss-travel-pass.html

Steven, details on the discount for the Swiss Travel Pass can be found here.

https://www.myswissalps.com/forum/topic/swiss-travel-pass-25-off-until-11-december-2021

The promotion starts on Nov. 11th.

Thanks Sean!!! I started a new post with details of the sale so everyone will clearly see it. This is a great deal!!!

Sean , Many Thanks ! I'd have missed that if it wasn't for you ! , my best , Steve

Oops ! Thanks Carrie , I misread the reply , I thought it was from Sean . In any event , Thank you both !

As far as the first part of the trip goes, you say starting in the Netherlands, I am going to assume you mean Amsterdam. You can buy a Super Sparpreis Europa Ticket from Deutsche Bahn at least a couple months in advance for 49.90 EUR each. That is a direct ICE leaving 7:38 am. Would recommend buying seat reservations for 4.50 EUR as this train can get crowded. Or for 63.90 EUR, you can go 1st class and the seat reservation is included. Train takes 7 hours to get to Basel.

From Basel, you can use the first day of that 3-day Flex Swiss Travel Pass to continue to Zermatt. You said you are spending 3 nights total in Switzerland, so that means 2 nights in Zermatt.

If you are coming from elsewhere in the Netherlands, that train also stops in Utrecht and 's-Hertogenbosch so you can pick it up there with a connection.

The train from Tirano to Milano Centrale is a regional train that is always the same price, 11.50 EUR. It goes from the Nord station across the piazza from the Swiss station. Trains go every hour at 8 past the hour (except no train at 2:08 pm). At Milano Centrale it is a high speed Freccia train to Florence.

Thank you all for your thoughtful replies! I'm still continuing to look into this, as I have time and energy. Rest assured, I'm reading all replies and am grateful for your input.

Cat & Greg, pls note that when you price Swiss Rail tickets, the assumption is already made that you at least have the Half-Price Pass. The prices therefore are not the full prices.
Safe travels!