Train from Montreux to Luzern and stop in Interlaken

Yes trains to Luzern (and Brienz) leave from Ost, because the train from Zweisimmen is standard gauge, and train to Luzern is meter gauge, so that is where you change trains. The Lake Brienz boat dock is also right behind Ost. I've never been around West station. It is also where the meter gauge train to Lauterbrunnen and Grindelwald leaves from, so the one day we visited from Wengen, we staid in that vicinity. Lots of restaurants and stores nearby.

There isn't particularly an "old town" area in Interlaken, in the way you might see in other European towns. Most of the development was done in what we in England would call late Victorian times - the late 19th century into the early 20th century, and then many shops were redone into late 20th century modern.

Is there something in particular you are hoping to see? I've visited the Berner Oberland often and on some trips have stopped in to Interlaken and in the early days used Interlaken as my base (before I tried staying up in the mountains in Mürren and then haven't stayed in Interlaken since) so I have a good idea of what's there - I've walked around most of the town and driven around much of the rest. Are you perhaps referring to the neighborhood of Unterseen? It is across the river and mostly a bedroom community.

Are you looking for the grand hotels? They stretch along the road between the two stations, perhaps a bit weighted towards the west station. The Schue cafe is next to field where the hang gliders land and is towards the east station. It is only about a 20 minute walk between the two stations - 1.6 km, almost exactly a mile.

The town is pretty much the result of winter, and later to a smaller extent, summer, tourism by initially British who did a lot of the development (along with St Moritz) so the use of the Victorian description is quite apt. It has always provided all the things that tourists need such hotels, large and small, restaurants, shops (tourist shops primarily, not so much village shops - such as watch, knife, jewelry, fast food, camera supplies and for the pleasures of the flesh, etc.,). If you are at the west station you will know you are walking to the great hotels by looking in the distance for the McDonalds. Make for the McDonalds and after you pass it the road will turn into the Hoheweg, the high street. From the east station come out and find the Coop supermarket across the street, and turn right along the edge of the station - the straight road will take you straight to the west station and the Hoheweg.

Can I strongly suggest that you use Google Street View to "walk" the streets around there and decide before you go if it will meet what you are looking for...

The two stations take their names from their location in the town, Interlaken West (the same word in English and German), and Interlaken Ost (ost = east). Interlaken West is a standard gauge station, main line trains arrive from the rest of Switzerland, and from Germany and France. No trains terminate at West, they all go through to Ost to terminate. The standard gauge tracks end at Ost, and the narrow gauge tracks from Luzern (Lucerne) terminate at Ost too. Ost is also the start of the narrow gauge railway up into the Lauterbrunnen valley and the Grindelwald valley, so if you are going up into the mountains (or to Luzern) you will change trains at Ost.

The two big multistory supermarkets in town are at the stations - Migros at West, Coop at Ost. Both have eating areas and everything you could ever want to eat or take camping or have in a holiday apartment.

Please say just what it is that you are looking for and I can help.

Interlaken’s best feature is actually the ost train station where you’ll change trains to go up into the alps, Interlaken itself isn’t in the alps and really rather a dull waste of time in itself.

Just agreeing with the others. Interlaken has Migros and Coop, which in addition to their large supermarkets, have lots of other general merchandise at reasonable prices. For instance, when my day bag tore, I bought a small backpack at Migros for 20 CHF. I still use it often, and it's a treasured souvenir.

The mountains villages in the Berner Oberland have small Coop grocery stores, but for most other merchandise, Interlaken is the closest place.

There is a museum of tourism that took me about a half hour to see. If you like old Victorian era travel posters, this may be of interest. If you don't like that sort of thing, no need to detour for it.

Interlaken also has large hotels, jewelry stores, sex shops, casinos, and large tour groups (many from the Middle East and South Asia). If you are not looking for these things, and don't need anything from Migros or Coop, there is no need to stop in Interlaken longer than it takes to change modes of transit.

Thanks everyone! I just didn’t want to miss something along the way to Lucerne. From what you say I’m not missing much in Interlaken! We will be visiting the mountains on several day trips from Lucerne . I had read about the Ballenberg Museum in Brienz. Should we stop there instead?
Thanks again

which mountains are you visiting as day trips from Luzern?

Please say it isn't the Schilthorn, the Jungfrau, or the Eiger... you are 20 minutes away from Lauterbrunnen at Interlaken Ost. It is too far to easily do as a day trip from Luzern, and the in the 2 hours plus travel time up into the mountains the weather could so easily change. The mountains have their own weather. Generally if the mountains will be clear that day it will be in the morning, and often clouds form near the summits near noon, and there can be thunderstorms in the late afternoon. Or not. Best to check locally....

I've never been to the Ballenberg museum. I always have plenty to do outside so haven't gone. I haven't gone to the model railroad museum near Interlaken West for the same reason.

Brienz is famous for wood carving.

You could do worse than leaving the train at Interlaken Ost (you have to anyway coming from Montreux, and you may have to change at Spiez as well as the change you know about at Zweisimmen) and taking the boat to Brienz instead of the train. The boat is a very scenic ride, depending on how you are getting your train tickets to Luzern it may be included, and you get right up close and personal to the Giessbach waterfalls (plenty of other things to do at Giessbach, just ask - including one of my favourite walks), and the boat docks right at the Brienz train station, timed to meet the train.

The train to Luzern turns around (changes ends) at Meiringen, the next stop after Brienz. Meiringen is worth some time in my opinion. It has a nice village feel, has the funicular up Reichenbach Falls of Sherlock Holmes fame (or Moriarity infamy), and is where Swiss meringue was invented - hence the name. You won't starve in Meiringen. Nice views too.

The Ballenberg Open Air Museum is indeed interesting. It has historic structures brought from all over Switzerland. Furthermore, you can go into any area not specifically barred, so be sure to climb stairs, open doors, etc. It's a particularly good thing to do on a cloudy or mildly rainy day, but beware - it it's really raining, the paths connecting the structures become very muddy (ask me how I know).

There are bus stops at both ends, so you can take a bus from Brienz to one entrance, walk through the museum, and take a bus from the other entrance (which just became your exit) back to Brienz. No need to double back, which is good as seeing the whole thing requires a lot of walking.

Entry is free if you have a Swiss Travel Pass, and discounted with some other travel passes, so if you have one, be sure to check if it qualifies you for a reduction.

Here's the website for more information: https://www.ballenberg.ch/en/

All that said, if the weather is good, I'd prioritize time in the Alps over this museum.