So confused! Best way to get from Murren to Varenna?

My first question, you say "Sunday (July 29) and I am having trouble finding trains out of the Berner Oberland on that day.* - where are you looking?

Swiss train times have been fixed and published up to December this year, and all Swiss rail routes have at least one train an hour. THERE WILL BE TRAINS and they are all listed on the SBB website ( https://www.sbb.ch/en ).
You do not need to tell the SBB website what route you want, it will always find the quickest route.

But, Italian local trains (including those to Varenna) have yet not been published past 10th June. They will be 95%+ the same as current, but just not officially available yet.

So, go to SBB website, and enter "Muerren BLM" to "Varenna-Esino", with a date of Sunday 3rd July, and a time. This will give you the options.
The most scenic route would be via St Moritz and Tirano, over the Bernina route. But I don't think you have time to do this all in one day, it would require an overnight stop en route.

Here is one resource to help your planning.

https://www.rome2rio.com/map/M%C3%BCrren/Varenna-Esino

Not sure you can avoid 7+ hours of train travel, short of chartering a plane. A hired car and driver may not be much less

Hopefully someone else here has more knowledge about the solution to your needs and desires

There is another poster having the same problem going the other way. There should be a big sign somewhere.

PEOPLE, DO NOT PLAN YOUR TRIP TO GO BETWEEN THE BERNER OBERLAND AND VARENNA ON THE SAME DAY.

Yes they are both desirable destinations, but very awkward to get between if you are trying to use those scenic Swiss trains. It is an all day slog with a record number of train changes. Suck it up and use those Base tunnels that the Swiss have spent so much treasure to build. Scenery is nothing to write home about, but they get you where you want to go. Or add days to your trip to spend some time in Luzern and St Moritz. Instead of Lake Como, visit Lake Maggiore.

Following on from Chris' advice to search for an earlier date, such as June 3:

• The fastest connection time from Muerren to Varenna is 6h 17 min, but requires departing by 7 a.m. and making 6 transfers.
• You could depart closer to 9 a.m. and make 5 transfers, but total travel time is closer to 8 hours. This one would probably be my choice.
• There often is a trade-off between shorter duration and more connections.

Another option that includes some legs not reflected in the train schedule (but also not any faster or simpler) would be:
Search a train schedule from Muerren to Lugano (consistently 5h 19min), then look at taking local bus C12 from Lugano to Menaggio (no date on this timetable, then a ferry to Varenna.

You cannot go up one side of the Jungfrau and down the other. The top of that mountain is a dead end and only a sightseeing destination.

Actually, you “can” travel over the Jungfraujoch to Fiesch (just east of Brig), but it is a two-day glacier hike:

https://www.aletscharena.ch/life/shows-events/events-calendar/event/?event=2-day-glacier-trip-jungfraujoch-konkordiahuette-fiesch&date_from=2016-10-04&date_to=2018-10-31
Something I would love to do, but probably will not,due to time constraints.

The Bernina Pass route takes you far to the east, and then you have to come back west to reach Varenna. You can see this from the Swiss rail map. But you can also see a more direct route, now covered by the Gotthard Panorama Express:

https://www.sbb.ch/content/dam/sbb/de/pdf/freizeit-ferien/ferien-kurztrips-schweiz/internationale-gaeste/sts-geltungsbereich.pdf

https://www.sbb.ch/en/leisure-holidays/travel-in-switzerland/panoramareisen/gotthard-panorama-express/timetable.html

This would be a long day with many changes, using cablecar, trains, boat across Vierwaldstaettersee (Lake Lucerne), then another train on the Gotthard pass route, bus from Lugano to Mennaggio, and ferry across the lake to Varenna. With the right attitude and an adventurous spirit (and maybe a day left on a Swiss Pass to cover the cost) it could be a fun day.

But if you just want to get there, take the Spiez-Brig-Milan route with the deep tunnels.

Hi, I also need help to get from Varenna to Grindelwald (3 nights). Then to Lucerne. Parents +2 adult daughters. Goal is most scenic and not too long? Originally thought Milan,Brig,Spiez (fastest), but concerned that missing the Bernina(local train) route would be a mistake. There appears to me three major ways to Interlaken, correct me if I’m wrong.
1. Tirano,St. Moritz, then either through Zürich,Bern,or though Lucern to Interlaken
2. Lugano, Bellinzona, Fluelen, Lucern to Interlaken
3.Milan, Brig, Spiez to interlaken
Trying to calculate the time of each route , train changes, price, tickets
Thinking about not going through lucerne as we will be returning to lucerne on same route unless it’s the best way. Of course your trip is in reverse direction. I hope this helps a little. ;-) Clearly I would have planned this differently. I’m leaning to #1, Also thinking to make the decision day of the trip if the weather is nice take Bernina, if the weathers bad go through the tunnel.

yankeebeach, Yes, your route options are the same as SPR. A timetable search www.sbb.ch will answer most questions except "most scenic." When you enter your start and end points, it will default to the fastest options. If you want to make a specific detour, then you can add a "via" midpoint to your search, such as via Tirano, revealing that it adds 3 hours to the total travel time (but I think would be more fun and scenic).

The connections go like clockwork. Shop for a day ahead for enough supplies to eat both breakfast and lunch on the trains.

Ticket price is not likely to be the deciding factor in your choice. However, a route via Tirano spends less time on Italian railways, versus doubling back to Milan, so would be almost entirely covered by a Swiss Travel Pass, plus about $10 per person between Tirano and Varenna.