Recommend Berner Oberland Rail Pass?

I am thinking that we should purchase our rail tickets from Zurich to
Gimmelwald and the Zermatt to Geneva on Trainline soon. Is it
recommended to get those tickets through Trainline and do that soon?

There is no need to get involved with trainline, unless you like to pay more for your tickets. There is also no need to buy tickets in advance. What would probably be a good idea is to get the Half Fare Card (which you can get on arrival at the airport). The Berner Oberland Pass may be a good option since you plan to spend a significant amount of time here. With the HFC you get a discount on all normal tickets, and on the Berner Oberland pass.

What you could do is:
- When arriving at Zurich airport buy the HFC, a ticket to Gimmelwald, and a 6 day BO pass starting on the next day. Then travel to Gimmelwald. Then on day 6 travel to Zermatt, via the Lötschberg route. That way you would only need an additional ticket for Brig Zermatt. Then in Zermatt use the HFC to get discounted tickets for the mountain railways and cable cars. And then on the last day just buy a ticket to Geneva.

Many of us recommend getting both the Half Fare Card and the Berner Oberland Pass. If you buy the 6-day Berner Oberland Pass, the 96-CHF discount you get if you have the HFC will almost cover the 120 CHF cost of the HFC. You then have the HFC to cover 50% of the cost of your travel outside the BO validity area.

Here is the price list for the BO Pass:

https://www.berneseoberlandpass.ch/prices-tickets/

And here is a map of the validity:

https://www.berneseoberlandpass.ch/assets/Uploads/Geltungsbereich-Berner-Oberland-Pass-2024.pdf

A 6-day pass will cover the 5 full days in the BO, plus either your arrival day or your departure day. WengenK has suggested you use it to cover the day you travel to Zermatt, and that sounds good—-just remember to follow the longer route via Kandersteg between Spiez and Brig. The faster route is from Spiez to Brig via a deep tunnel and IC trains, and this is not covered with the BO Pass.

So with this plan you will need tickets from Zurich airport to Gimmelwald for Day 1, Brig to Zermatt on Day 7, and Zermatt to Geneva at the end of your trip. There is no price advantage to purchasing these in advance, but you can buy them on SBB.ch if you wish. Or buy them at the station before boarding the train.

I do like to purchase our Half Fare Cards and Berner Oberland Passes in advance, and print them out as well as having them on our phones. That’s just my way of doing things.

I recommend the HFC and BO Pass, but I do NOT recommend buying them at the station. They will give you paper tickets with a bar code on the back. The scanners at numerous gondolas and funiculars could not read the tickets. We had to wave over and employee each time. People who had the tickets on their phone had no problems using the scanners. So buy the HFC and BO Pass online. The HFC can be purchased through the SBB app. The BO Pass can be purchased here: https://www.berneseoberlandpass.ch/

Do not purchase things from trainline. Only purchase tickets from the official website - sbb.ch/en or just go up to the ticket counter and tell them what you want on site (they speak English)

We had paper passes and never had a problem. However, we watched as some people had trouble getting their phones to bring up their passes for controllers to scan in the trains, the opposite of travel4fun. Six of one, half dozen of another.

Buy the BO pass as well, just for the ease of not having to worry about buying a ticket every time you want to go somewhere, that's a major hassle. We stayed in Gimmelwald for 5 days (OMG, the best!!! Esthers Guesthouse for the win, we could have stayed another week). With the BO pass you don't have to think twice about whether you should get on a cablecar due to price, you just do it since it's already paid for. If you can get an electronic version that would be better. We had the paper we bought at the station, but you did have to flag down an attendant on occasion to get through which would be better to avoid if possible. Have fun!