Recommended places to eat in these three towns?
Have you looked up the area on Chowhound.com?
In Luzern we stumled on an outdoor cafe in the Old Town area with great fonduue we hadnt had it on the trip til then0. Warm afternoon and really enjoyed it. You can chance upon good, inexpensive food wherever you travel. We travel with the names of only a very few (special0 restaurants. We generally sumb;le upon (or get local suhhestions) for some really enjoyable meals.
We prefer to save money on food wherever we can in Switzerland so usually eat at the Migros supermarket cafeterias, or if not available, at the Coop supermarket cafeterias. Good nutritious, reasonably inexpensive by Swiss standards. Near Interlaken WEST station is a large Migros. Across from Interlaken OST is a fairly large COOP. Another alternative is department stores. Most Swiss cities have a Manor department store, and most of those have a Manora restaurant within. They are a step up from the Migros.
One of the very few sit down meals I had in Switzerland was at Montreux's Hotel de la Rouvenaz, Rue du Marche 1, just across the street from the water. Wonderful meal, at a price that was very decent for Switzerland. Tried Manora in Luzerne, and that was the first and last time I ate there! Awful! Picnic supplies from the local markets and grocery stores were very tasty, and relatively inexpensive.