Schlepping 1 large suitcase on trains

You are good now, why add a major headache? The Interlaken-Lauterbrunnen transfer is short and involves going down the stairs to the underpassage and up the stairs to the new track. Of course, if you miss that connection, there will be another train in 30 minutes.

My wife and I travel exactly as you are now packed and we never had any troubles.

That sounds like a nightmare instead of a good idea. Go with your manageable weight and size for efficient train travel.

Watch the few other travels moving their worldly goods along in giant suitcases, strugggling to get up the steps or looking for a place to stow it if the train is full.

IMHO - When space is limited, it's much easier to find room to store two smaller bags on a train as opposed to one big one.

Just a thought of less bags to keep track with and only 1 bag to unpack... I was expecting that each station will have escalators at least and that it's off season-less crowds ( will be there tomorrow) thanks for the tip nonetheless...

In Bern there are two main ways to get from the curved tunnel beneath the tracks up to the platform. If you turn one way you have a set of quite steep stairs - I've never counted them but around a story and a half perhaps. If you turn the other way there is a ramp. It is only a ramp and a fairly steep though long one. Once you are at the top you may have to move down the platform to get to the train you want, because the platforms as at all large and medium sized Swiss stations are divided into zones A, B, C, D and your train or class of train may only stop in parts of the platform.

The only lifts and escalators are right at the very D end of the platform and go up to the road bridge outside. If you want to use them to reach the platform you actually go outside the station to do that, and if you want to get to the concourse in the station it either down onto a platform then down into the tunnel from the platform using the ramp or stairs (ramp is closer, the stairs are in the middle of the A end) and then the curved tunnel into the concourse, lower level. There are then escalators to the bus station and the concourse upper level. Or you can cross the street upstairs and walk all the way around outside to the entrance by the bus station.

All in all, smaller luggage equals easier experience.

This behemoth that you are considering changing to - does it have 2 wheels or 4?

Please return and report your experience.

About the crowds - maybe so in Interlaken and Lauterbrunnen.

Not so at Bern and Zürich. Most of the people using the stations there are commuters and other workers and people on business. Tourists are a very small percentage. So off season means everybody is at work - probably bigger crowds than in August.

"I was expecting that each station will have escalators at least"

That shows you where expectations get you!

Some stations have elevators; some stations have escalators (although I don't remember these in Switzerland); some station have ramps (often steep); and some stations only have stairs. If you need or want anything besides stairs, you have to check the specific station in question. You also have to hunt around for the part of the platform with what you want. For instance, I remember in Luzern Lausanne that one passage had elevators, and the one on the other side had ramps.

I agree that keeping track of fewer bags is a bit easier. But in every other way, your original packing plan is far better - stick with that. Since there are at least two of you, at every transfer point, just make sure all of you count four bags off and four bags on.

Edited now that I see Chris's post about Luzern - I was misremembering, and it was Lausanne that had elevators for one passage and ramps for the other. It was memorable because the Coop grocery in the station was only accessible via the passage with ramps, not the one with elevators.

4 wheels spinners-hard shell. What about going thru Luzern? I'm aware it is a longer trip, but scenic..and maybe easier??

I was expecting that each station will have escalators at least and that it's off season-less crowds

No and yes in that order (off season in the Berner Oberland, no change for how busy transport is outside tourist areas).
Escalators are a rarety and in larger stations only. Usually steps down to an underpass, plus a ramp suitable for wheelchairs and others who don't like stairs. Lifts (elevators) are being added slowly to major stations. Escalators and lifts are expensive, as you need one for each platform.

I guess you mean "Zürich Flughafen" (Zürich airport) station, not the one in the city centre. That has escalators to both platforms. You go down more than one level to reach it.

Here is a plan of Bern station: https://www.sbb.ch/content/dam/infrastruktur/trafimage/bahnhofplaene/plan-bern-plakat.pdf
The main entrance is an underpass, with both steps and ramps down. There is also a newer bridge entrance at the far end of the platforms, with escalators.

Interlaken Ost station is stairs and ramps down to an underpass.

Lauterbrunnen station is tiny, all on one level.

Luzern station is a terminus (dead-end) station. You walk to the front of the train and are at street level. Ticket sales are below ground level, with access by escalator, same level to go under the adjacent street.
Plan here: https://www.sbb.ch/content/dam/infrastruktur/trafimage/bahnhofplaene/plan-luzern-plakat.pdf

I hope your two carryons have wheels, that will make it all a lot easier. Definately do not re-pack into one bigger case.

Every man/woman for themselves!! My husband and I (fit in late 60's) travel with a 23" wheeled checked bag each and a backpack each. If I cannot manage it on my own than it is too large and heavy!!! This serves is well regardless of the length of the trip ....1 week-4 weeks. We use public transportation almost exclusively and this works for us.

The odds are really against the big guy ...Just found out from the SBB app that there's some sort of work going on between Brienz and Interlaken.. Ok I am aborting the "One bag to rule 'em all".

Thanks for the links Chris, first time I came across with these, will definitely absorb it since we still got a few hours to do before the flight tonight.

I think you are much better off with each keeping track of your own roller bag, than sharing a large bag and wondering who is keeping track of it.

I think you're on the right track now, but I'd also not assume that your hotels all have elevators, unless you've checked. Even just hauling the big bag uphill for a block (e.g. from the Lauterbrunnen station to the Hotel Oberland, where I stayed recently) would be strain on the designated hauler.

I took a bag that weighed close to 40 lb. on my 2015 trip. (Believe me, it wasn't clothes, but no matter what the excuse is, it was way too much weight.) It was indeed to pain to pull that thing through Europe, even aside from all the flights of stairs I had to deal with. A large bag can weigh several pound more than a smaller bag, and those pounds count just as much as the weight of the things you put in the bag.

A heavy bag is even more fun (not) if you're traveling in hot weather.

The best strategy for public transport is that each person is responsible for his/her own luggage.

I remember the "sherpa husbands" on recent train trips in Germany and Switzerland. These men (usually seniors) would try to move all of the baggage (usually oversized) for both themselves and their wives all by themselves. They created nothing but bottlenecks and ill will just about everywhere they went as they blocked other travelers from the exits who were also trying to make connections.

I realize that there may be some medical conditions that would mean a person may not be able to handle his/her own luggage, but I don't think that this was the case for most of these groups. I admire chivalry until it makes me miss a connection because they are overwhelmed with luggage and going the "wrong way" down the aisle to get more.

Havng just returned from a trip where my wife had a 28”, I can say DON’T DO IT !!!

Brava, Carol. I totally agree.

There are few things more frustrating than getting blocked from the train exit by someone trying to handle too much luggage. We saw one man line up three large suitcases by the door ( he apparently knew which side to get off, or else he guessed and was lucky.). When the door opened, he got off without any bags, then turned around and unloaded the bags one at a time down to the platform, where they still hindered exiting by other passengers until he and his family ( wife and teen daughter) moved them back.

he apparently knew which side to get off, or else he guessed and was lucky.

On German and Swiss trains (and I guess some others as well), it is part of the on-train recorded announcement "Nächste Halt xxxxx, Ausgang Fahrtrichtung Rechts" (or "Links").

I have seen groups, or even couples, where on gets off, and the other stays on handing all the cases down, one after another. Totally blocks everyone else, especially those sensibly carrying their one case and wanting to get off (and possibly catch another train).