preliminary planning question?

I would spend 3 nights in Muerren at least. That gives you one day for any hikes on the Muerren side and another day for hiking on the Wengen side.

One of my favorite easy (really almost level) hikes is Mannlichen to Kleine Scheidegg. You'd take the cog train from Lauterbrunnen up to Wengen, then walk a block to the Cable car station and take that up to Mannlichen. Follow the well worn trail to Kleine Scheidegg walkig toward the Eiger, Monck and Jungfrau mountains. Stunning views up and down into the valleys. You can get the cog train back down to Lauterbrunnen from there.

Walking along the river on the Lauterbrunnen Valley floor is also very easy. From Muerren you can take the gondola down to Stechelberg, walk the valley to Lauterbrunnen and then go back up.

There are a number of easier hikes above Muerren as well.

in my opinion you may not be cramming too much in, but you may be trying to cram about the right amount of stuff in too quickly.

So if that's all the time you can muster, then yes, I think it is too much. All excellent destinations but you'll see more of what you don't see than what you do.

since this is your first post here, welcome to the Forums, we don't know how much European travel experience you have. 2 nights only gets you one full day of sightseeing. The day before is taken up with moving and settling in, and maybe a bit of looking around after check in so you can find dinner. The day after is moving again after checking out. You'd be amazed how much time that can take. I am not trying to teach you to suck eggs, in your late 70s and early 80s this may be old hat to you, but perhaps not others reading. One night somewhere gets you a look around and a place to lay your head.

I want you to be able to take the time to compose photos, get the light right, look for the best shot.

I'd suggest either stretching the time or taking something out. For me, as someone who has gone there multiple times (and not such a hiker) 3 nights is the absolute minimum in Mürren. Are you intending on either of the big high altitude draws, the cable car up to the Schilthorn or the train up to Jungfraujoch?

Do you know what time your flight home from Zürich airport is?

Will you have lots of cruise luggage? If so, what will you do with it? You will need to get it on and off the trains by yourselves - no porters. I'm 70 and my wife is 74, one piece of carryon size each is plenty for us to manage (she is also visually disabled and wobbly so perhaps not a fair comparison).

Since you are not hikers, instead of Murren consider larger and very scenic Grindelwald. We spent a wonderful week there and visited Murren, Wengen and more. Cars are allowed in Grindelwald.

Stay at Hotel Balances on the river in Lucerne……get a balcony that overlooks the river and enjoy the view…..LOVELY…….then on to Murren or even stay in Wengen……both are wonderful though we love Lauterbrunnen……and take the hikes advised above….they are great….make sure you see Kleine Scheidegg and eat a lunch there…….Bern’s streets are fun but the mountains will have captured your hearts…..Zurich is a nice city and you will need to get back there to travel…..it has some fun streets to walk and shops to see…..

My next trip to CH is going to include the Lauterbrunnen Valley but when I go, I’ll spend a minimum of five nights so I have time to experience the top must see and dos. When you’re staying in the mountains it’s good to add a night in case the weather doesn’t cooperate.
You may want to ride the Schilthornbahn cable car and the Jungfraubahn train too. The Männlichen hike to Kleine Scheidegg is easy I’ve read and plus you want to explore the valley. Four full days (five nights) is what I suggest.
I’ve been to Bern and it was OK. I believe you can float along the river during the summer so taking photos of it might be worthwhile. You can spend a night and take a direct train from Bern to Zurich’s airport Flughafen train station (1h 30m) as early as 4:18a.

Thank you to all who responded to my questions...Your suggestions are very much appreciated. I think I will increase our stay in Murren and maybe skip Bern. Also thank you for the specific suggestions for hikes, day trips, etc.
I"m looking at lodgings and find that Switzerland is pretty pricey (duh..should have known that!). Does anyone have suggestions for reasonable lodgings in Murren (need en-suite bathroom). ?

Denise from Chalet Fontana has an inexpensive apartment attached to the Chalet Fontana (we liked our stay in the main facility but there are no en-suites). She is an absolutely lovely lady.

She may even have another facility but I don't know anything about it....

Her website isn't exactly cutting edge, and is a little old, but who cares? http://www.ferntree.ch/chalet/fontana.htm

Yes to skipping Bern. End in Luzern, where you can take a train directly to the Zurich airport in about 1.25 hours. When we did the cruise, we went to Luzern for three nights and had plenty of mountain time. You have to monitor the weather, and be ready to go up the mountains first thing in the morning when the weather on top is clear. You can cruise the lake there as well.

If you're on a Viking cruise, they will arrange to have taxis waiting for you at the disembarkation point, to take you to the SBB rail station.

Thanks again for all the help! I appreciate the feedback. I think I"ve got it together now...Take the train to Lucern for 3 nights and then on to Murren for 4 nights and then the train to Zurich for a night before our flight home. This way I think we'll have time to appreciate a few places rather than a quick glimpse of several. I even have booked our lodgings. But any suggestions for special things to do, places to eat, sights to see in Lucern, Murren and Zurich... bring 'em on!! Thanks and Happy Holidays to all you good folks.

We are planning the same cruise with 6 days after BUT cruise ends 4/29 and so time window 4/29-5/4…not mid June.
The schitterhornbahn concludes scheduled maint 4/28 but unsure if this trip is worth it in early May.
Thoughts?