Itinerary help please! 2 weeks in Switzerland & Northern Italy

Welcome to the Forum!
You have really done your research and are well organized. Also so happy that you have lodging booked.

Everyone is confused about the Swiss train passes. Most folks do ok with the Half Fare Card and a BO Pass.
However, the ease of the STP is worth something to me, and I usually find myself doing more things since I have it. However, There's no way around penciling out the cost of each trip, and adding it all up.
Then there's variables : in Lucerne, travel to Mt Rigi and Stanserhorn are all covered by the STP, and Pilatus only discounted.
Download the SBB app. Note that the SBB app assumes you have at least a Half Fare card, so double those prices.
You have a great trip planned in this beautiful country. Safe travels!

You have a very full schedule, hope you like being on the go! I'll just comment on Days 4-7 & say some of it is not realistic. You'll also need to be flexible with these dates and use your nicest weather days for your mountain activities (Day 5 & 7)

Day 4: To do your plan, you're going to want to leave early AM. Train from Luzern to Brienz, store your luggage at Brienz to do the Brienzer Rothornbahn (get a seat reservation ahead of time, as it's very busy). After lunch, come back down to Brienz, get your luggage and get on the boat from Brienz to Interlaken Ost. Enjoy the views from the boat and don't bother getting off at Iseltwald, it's chaos because of the Asian Netflix show and honestly prettier seen from the water at this point. Get off at Interlaken Ost, check into your airbnb and walk around for dinner.

Day 5: Put Wengen on Day 7 to give more time on the Murren/Gimmelwald side of the valley.... Interlaken Ost > Lauterbrunnen > walk the valley to Stechelberg > Gimmelwald > Murren > lots of great hiking opportunities here (especially up at Allmendhubel) or just wander the village > Grutschalp > Lauterbrunnen > Interlaken Ost

Day 6: Doing Gstaad in addition to Lake Thun and Saneen is waaaay too much. Just enjoy Lake Thun and leisurely get off at some of the lovely stops. There are castles at Spiez, Oberhofen and Thun, in addition to the caves, etc. This is a full day without adding in Gstaad, which is over 2 hours each way.

Day 7: Interlaken > Grindelwald > Grindelwald First/Bachalpsee (be prepared for crowds) > Grindelwald > Mannlichen > Wengen for dinner > Lauterbrunnen > Interlaken Ost

We used the STP. I found that we were much more apt to do things covered by the pass because they were already “paid for” rather than paying for each activity, ie. boat trips, cable lifts, buses, museums. If I had had to reach for my wallet each time, we probably would have passed on a lot of fun things.

First post for me here too, but my wife and I visited several of the areas on your itinerary last September (2023) on an 8-night trip, so I figured I would chime in. I would agree that the Lake Brienz boat tour is very busy, but we were glad we did it. We almost would rather have one more day hiking in the Lauterbrunnen valley vs. the boat tour, but both were great. I prefer less crowds though.

Also agree that your days seem a little overly ambitious, but if you are up for it, then go for it. We stayed three nights in Wengen and used that as our base for that area, then three nights in Zermatt, then back to Zurich for two nights.

For the Wengen portion of our trip:
Day 1 - Train from Wengen down to Lauterbrunnen, Staubbach falls short hike up and down, hiked across the valley to Trummelbach falls, rode the "elevator" up and hiked down, rode the bus back to Schilthornbahn, rode the gondola up to Wengen for dinner with a view, then back to Wengen by about 8:30pm. That was a fantastic, but very long day.

Day 2 - Train(s) from Wengen to Interlaken, Brienz boat tour to Brienz, Train to Grindelwald for walk to dinner, train(s) back to Wengen. Also a very long day.

I think it would be nearly impossible to add much more to those two days, just as a reference and we were moving pretty efficiently but also enjoying everything.

In Zermatt, we went a little slower but there is a lot to do and see there, more so than the Lauterbrunnen area for sure. We did a few hikes, one up to the Edelweiss mountain hut, which was closed but we didn't care too much as we were there for the hike. That day we went back down to Zermatt for lunch, and then took the tunnel train to Sunnegga for a short visit in late afternoon with spectacular views. I'm sure not quite like the Gornergrat but it was great.

The next day was expected to be quite rainy in Zermatt, so we took the train into Italy and had lunch in Domodossola and hiked up to the Sacro Monte Calvario site which was very cool.

That will be a fantastic trip!

Wow, this community is amazing! Thank you so much to everyone for your very helpful replies.

@Pat - I appreciate the information you shared about the different passes. I will look into seeing which pass makes most sense for us. Thank you! :)

@wanderweg - I have gone ahead and edited our days 4 - 7 with your suggested changes. These days now look much more feasible and enjoyable. Thank you so much for sharing your knowledge! :)

@Gigi8 - That's a great point - if we do end up buying the STP, we'll definitely make good use of it. Thank you! :)

@cyclist_001 - It sounds like you & your wife had an amazing trip last Sept! Thank you so much for sharing a portion of your itinerary. It helped me edit my days around to incorporate your suggestions :)

Once again, many thanks to everyone who kindly took the time to send suggestions! Our trip already looks much more organized and we are so excited :)