Interlaken to Venice S. Lucia

When I price it though Trenitalia, I get 220.60 EUR to go from Spiez to Venice S. Lucia. That is about $275 US.
You can get tickets from Interlaken Ost (its where the trains originate) to Spiez for 51.30 CHF for 4 adults and 1 child. That's is about $55 US. So that total is about $330, so the Trainline price looks good. SBB was asking 475 CHF for advance purchase tickets, about $508.

To get the Trenitalia price, you'd have to buy nonrefundable tickets today. You can buy the Interlaken-Spiez tickets once you are within 30 days of departure and you could get nonrefundable SuperSaver tickets. The full fare price is 11.40 CHF per adult and 5.70 CHF for the 12 yo. You might get a better price with SuperSaver tickets, but perhaps have to take an earlier connecting train.

SBB Is the train operator in switzerland. Using SBB.CH and putting Venice and Interlaken it bring up purchase option on that route. Connections in Milan and Speiz.

When you go to book, it it doens't let you book the Venice to Milan porition you can use the Italian Train operator TRENITALIA to book that portion. But with SBB showing purchase you might be able to purchase the whole route on the ticket.

Adding a twist: SNCF is on strike, and apparently are refusing to sell tickets for June 13th via Trainline.

With that nugget of knowledge, do I take my business elsewhere? Or is there hope that they will work things out? (Learning the ropes of train traveling I am!)

If I do what Sam & Chris suggest and buy the Spiez-S. Lucia tickets now, via Trenitalia, do you promise I won't pay big bucks later for a Interlaken-Spiez ticket? (I am lacking confidence with the waiting for cheaper price)

Again, as always, thanks for your sharing your expertise!

Swiss tickets are always (almost) the same price. The full fare ticket from Interlaken Ost to Spiez is 11.40 CHF per adult and 5.70 CHF per child (under 16) always. Now there are nonrefundable SuperSaver tickets that go on sale 30 days before the train date, so that could be up to 50% off. But these are released on at SBB's discretion and the level of discount varies. May or may not be available, or worth worrying about. The trains never sell out and with a train about every 30 minutes, they are not often even crowded.

Thanks Sam!

Swiss and Italian Railways are about as different in their pricing policies as it is possible to be.

For Italian long distance trains, the ticket is only good for the train listed on the ticket (same as air tickets are). And, the ticket also lists the seats which are reserved for you. And, there are big discounts for buying early. Buy on the day and you pay the highest price.

Swiss Railways have standard prices. You buy a ticket, and can use it on any train that day. There are no reserved seats, you can sit anywhere. They try to provide enough capacity so nobody stands, but don't always succeed on short distance trains in the rush hour.
Interlaken Ost to Spiez cost CHF 11.40, 2nd class with no discount card. That price is written in stone, and will apply to every seat on every train until at least the annual timetable change in December. So you can buy now on the SBB website, or at Interlaken station on the day, and it will be CHF 11.40

Please note I said you may have to change at Spiez, or it may be at Brig. This is because some of the trains to Milan are going Basel - Bern - Spiez - Brig - Domodossola - Milan. In which case you can get on board at Spiez and can buy a ticket on Trenitalia from Spiez.
But some run: Geneva - Lausanne - Brig - Domodossola - Milan. In which case you can't get on until Brig and will need to get Swiss trains (and tickets) to Brig and Trenitalia thereafter.
You need to look up the times, choose a time and see where you change onto the train heading for Milan.

That train routing you cited (7:29 to 14:10), it is an EC train originating in Basel and stopping at Spiez continuing to Milan, then you change to a Freccia train to Venice.

It should not be true that some web sites "are much cheaper than others" for booking the exact same train, especially on this route.

• Italy has advance-purchase train discounts with limited seats at each price point (so the cheapest rates can sell out while you're looking), but Switzerland does not really go in for that.
• Neither the Swiss nor the Italian railways can usually sell a train connection within the other country; only the leg departing their own country, so routes that change in Milan have to either be broken up or bought through one of the outside agents.

If you're sure that your family can be up on time for the 8:00 departure, SBB can sell the whole route, with connections only in Switzerland, at Spiez and Brig. They have it available now for 386.50 CHF for the family.