Montreux or interlaken after medical treatment?

Montreux may be a better choice. It has very mild and more predictable weather. If you feel better quickly, you can get an alpine experience by taking the train to the Rocher de Naye. Otherwise the walk from Montreux to the Chillon casle is very picturesque.
In addition, the CHUV in Lausanne is nearby and is a world class hospital in case you need care.

My suggestion would be to stay close to where you have the procedure done so that you can get follow-up care if necessary. I would be leery of traveling too far immediately afterward. You won't know if you'll be up to it, and you'll need to be careful to make sure your insurance will cover follow-up care in another country from which the original procedure was done. (And driving to mountain towns if you're even a little queasy...) The other thing I'd be a bit worried about is going to high altitude for recovery. I wish you the best.

Lucerne would be a good choice. Easy to get to from SW Germany, great scenery, can walk a little around town or a lot in the mountains. Super easy to get back to Zurich.

As Dina says high-altitudes can do weird things to your body. I wouldn't go up to the alps after surgery. Montreux is definitely a better choice. Very easy and scenic walking along the lakefront promenade, and relaxing boat trips on Lake Geneva.

I really like Dina's advice. A lot depends on the type of surgery. My wife has had surgery for a detached retina and we had to be very cautious about heights. Couldn't fly. We even had to stay on lower floors for a high-rise hotel stay in San Francisco during the recovery. But, if you must travel, both Interlaken and Lauterbrunnen are nice and level and both are at lower altitudes. I do like the suggestion for Lucerne but I do like Lauterbrunnen and possibly Muerren (at 5,200') a lot also. Just don't take any unnecessary risks.

Thank you all for your thoughtful responses. I am not having surgery but rather a radiation procedure. I may be queasy afterwards, but hopefully not. Do you think interlaken Will be too crowded with tour buses? Steves kind of knocks that as a destination spot. We did reserve a lovely sounding hotel on the lake in montreux.. Just don't want to miss out on the beauty of
the inerlaken area!!

I've stayed stayed in Interlaken several times. I've never found it to be crowded, it simply lacks the charm of the mountain villages. But on the plus side it's very functional, has an excellent range of restaurants, and it's location makes it easier to do day trips outside of the Berner Oberland in case of rainy weather.

Bonnie, Interlake is quite nice and it could be a bit touristy in the summer. I would suggest booking something in nearby Lauterbrunnen. You go to the Track 2A at the small Interlaken Ost train station and take the 22-minute very scenic train ride on the Jungfraubahn train into Lauterbrunnen. There, you will see the Alps on steroids in a way that you cannot see from Interlaken. And, you are just 22 minutes away. The two hotels to look at in Lauterbrunnen are the Staubbach and the Hotel Silberhorn. The Staubbach is less expensive but a bit more rustic. The Hotel Silberhorn (www.silberhorn.com) is a bit more expensive but it has a very nice restaurant. This hotel is not in the RS book but the restaurant is. We've stayed there and loved it. Very relaxing. Plus, once your luggage is all checked in, you have access 500 feet away to Muerren, Gimmelwald and Muerren or higher up to the mountain tops if you wish.

If you are going to be queasy you might be best off with a lakefront hotel room and beautiful view, where you can take short walks along the lake when you feel up to it. Water views are always calming and relaxing. The place in Montreux sounds nice. You could also consider Lake Lucerne (Vierwaldstaettersee), not the town of Luzern but one of the smaller lakefront towns like Weggis or Vitznau. You look across the lake at the alps and could ride the cablecar up to Rigi Kaltbad for nice short walks. We have experienced better views at Luzern area than Montreux area---Lac Leman always seems hazy, both when we have been there (twice) and in photos. Or you could choose based on whether you prefer to speak German or French. P.S. I found ginger to be helpful with queasiness after radiation. Wishing you good health.