How much currency to bring?

In the Netherlands, I am not sure you need any cash at all...
In Switzerland, you might need small amounts of cash for things like lockers and pay toilets, but at that rate even just 40-60 francs will go a long way!
And I would not bring the cash, I would just withdraw locally, especially since you have several credit cards.

Do not use a credit card for ATM withdrawals, use a debit card. Just notify your bank you will be traveling. Europe is ahead of us in transitioning to a cashless society. Your credit card with a chip will take you far. Just be sure you can “tap” it at home to be certain it works. Apple Pay is widely accepted. On a recent trip to Spain I found my iPhone was good for about 90% of my purchases.

you may want some Euro for Germany if you go off the boat on your own...

We returned two weeks ago from Viking's Rhine getaway going Amsterdam to Basel, with extra days on Amsterdam and Lucerne. Although I had euros (including coins for toilettes) we never needed them. Once in a bakerei I was asked if I would pay in cash for a small purchase, but they had a card machine I could have used. The boat excursions always had potty stops that were free. In Switzerland, we never needed cash although our Viking host said some places would take euros and give change in Swiss francs. Hope this helps.
Enjoy your trip!

We have been in Switzerland for over a week We took out 100 Francs from a BANK(UBS) atm at the geneva airport but have used just half of it mainly for small purchases to use the change for tips at restaurants where we felt the service was warranted. We could have taken nothing out and just used our credit cards as we have not stayed at hotels where one might want to tip bell hops etc. A few restaurants now have the option to leave a tip on the credit card but not many. We have been taking euros home over the last year for future trips given the reasonable exchange rate. It’s always nice to have euros for your next trip. Sometimes we have to pay cash for balances on lodging (private rentals) or private guides on arrival so having some euro cash on hand is handy depending on how much you might owe and how frequently your travel to europe.

We took out 300CHF at a bank machine in the Basel Train Station. During our 8 days in Switzerland we mostly paid with credit card leaving us with 150CHF. I thought I could use those as partial payment for our last night's stay at the Radisson Blu at the Zurich airport.....ha! Cash not acceptable there!
In retrospect 100 CHF would have been more than enough.

As others have said, minimal. We are in Switzerland now and basically try to have 5 Franc pieces —mmaybe 10 Franc notes for a bigger meal—handy for tipping. That’s about it.

I just returned from 2 weeks in Switzerland. I withdrew 50 CHF from an ATM upon arrival at the airport/train station in Zurich. The machine gave me a single 50 CHF note. I needed to use a toilet somewhere that day (or the next) in a train station and that required coins. So I purchased a sandwich and a drink at a convenience store to break my note into change. A few days later, I needed to do the same thing again. All other toilets that I encountered in my 2 weeks were either free or allowed the use of contactless credit card (my iPhone) to enter. For EVERY purchase I made other than the couple toilet stops, I was able to use my iPhone (with associated credit card) to pay. I never once took a credit card out of my wallet. On the last day of my trip, I had 32.15 CHF in cash left in my pocket from the initial 50 CHF withdrawal. I bought 30 CHF in chocolate to bring home and I gave 2.15 CHF to an attendant in the airport lounge at Zurich to empty out my pockets of any Swiss money. I was thrilled to be able to use my iPhone for purchases everywhere. So convenient.

Check with your bank about the fees charged for using the ATM. Historically, our bank did not charge exorbitant fees for using a foreign ATM. That changed during Covid. When we visited Switzerland in November of 2021, we learned that our US bank was charging $12.00 per ATM transaction. We spoke to the bank upon our return and learned that we could purchase foreign currency ahead of time for a flat fee of $7.50. Our daughter lives in Switzerland (moved there in June 2022) so we visit often. We now order currency approximately a week prior to departure. In Switzerland, we find that 250 CHF per week is the sweet spot. We use credit cards with no foreign transaction fee for nearly all purchases but have handy 5, 2 and 1 CHF coins for tipping and bathrooms. We also love the market days in Lausanne and cash is preferred by most venders. I just returned from Switzerland and the 250 CHF was sufficient for the week. Hope that helps.

Thanks rccherapist (and responders) for posting this! I had the same question (different travel itinerary)!