I was just in Switzerland and all of the little villages near Interlaken sounded nice but hard to tell them apart with out actually seeing them. So I bought a loop ticket in Interlaken Ost (main) train station. It was about 85 eu, discounted to about 65 eu with my rail pass.
Interlaken -> Lauterbrunne -> Wengen -> Kleine Shidegg -> Grindelwald -> Interlaken.
Each of these trips took 30-40 minutes and the trains were running about every 30 minutes, so I was able to hop off for 30-60 minutes, then take the next train for the next leg of the journey.
Here are my impressions :
Interlaken is a small city - ok but not particularly charming. The Untersee area has some older homes and buildings.
Lautenbrunnen is a very quiet hole in the wall. I walked 20 minutes from the station and saw one big waterfall, but that was the only waterfall I saw. Since its deep in the mountain valley, it does not get a lot of direct sunlight. There seemed to be half a dozen little hotels, but not much in restaurants or things to do. Its a good place for isolation and quiet.
Wengen - much more fun, and half the people around are wearing skis. There is a bakery/boulanger that sells pastries (sweet and savory), soup, and coffee. There are also several restaurants, a tourist information office with wifi, and hotels. Definitely a much more fun and lively place.
Kleine Scheidegg - This was not mentioned in guide books, but several locals mentioned this as a desirable place. Its not really a town at all - its a ski resort. There are maybe 3 restaurants with terraces, a few gift shops, and thousands of skiers. Its right in front of the famous Eiger mountain I think. There are dozens of ski paths. I believe the Jungfrau railway is from here - and is something like 160 francs (> $160) but I did not partake
Grindelwald - This is much larger city than any of the others, and in fact so large, that it would be too big to travel on foot. At that point I had enough fun, and didn't hop off, and didn't see much going on anyway.
There are also a number of smaller stops on request - which seem to be lesser ski areas.
Also, from Montreux, there is a panoramic train that goes through several towns including Gstaad - which is free with the rail pass. Gstaad is essentially a bunch of designer shops and a few hotels for high rollers.