My husband and I are planning a 15 day trip trip to Switzerland/Italy in late June/early July. We plan to fly roundtrip to Zurich, although we could potentially return from Geneva. Would welcome thoughts on the proposed itinerary especially where to spend our time on days 8-12. We have never been to Switzerland, enjoy hiking, scenic views, good food/wine, like both mountain and scenic views, and sunny weather. We plan to travel by train. (Ideally would like to stay one place during this this leg of the journey that could be a launching point for day trips or just a pleasant/scenic place to relax).
Day 1 & 2: Arrive mid-afternoon in Zurich on Day 1
Day 3: Go by train to St. Moritz
Day 5 - 8: Via scenic train to Milan, arrive in Camogli, Italy to meet friends (this part is set)
Day 8: Leave Campogli/Genoa areas and travel to either Lake Como, Lake Geneva, Interlaken -
would love advice
Day 12-15: Lucerne, take train to Zurich on final day and fly out mid-afternoon (could possibly fly out of Geneva instead and rework the latter part of this trip)

Any reason why you are not flying into Milan, back from Zurich/Geneve or the other way? It would free up one for visit instead of spending time and money back tracking.

Also, do you have compelling reasons to be in Zurich? You can bypass Zurich city completely. For example, you can stay in Luzern until your departure day. It is only 70 min by frequent train from Luzern to the Zurich airport. Same for Geneve. Unless you have a compelling reason to stay in Geneve, you can get to the the Geneve airport easily from any of the lake side city.

Even though public transportation in Switzerland is incredibly easy and efficient, I agree that you should explore open-jaw options so that you can avoid backtracking if at all possible.

I enjoyed Zurich for its museums and other distinctly CITY offerings. If those aren't of interest to you, then plan to spend your time elsewhere.

Is there a particular reason for St. Moritz, and for just 1 full day there? You might want to consider a few days (plus) in the area, and perhaps consider staying in one of the less heavily touristed towns.

I haven't been to Lake Como, but have visited parts of Lake Geneva and the Bernese Oberland and think either could suit, but it really depends on YOUR interests. You might want to consult some good guidebooks (I found the Michelin Green Guide and the Rough Guide most useful for Switzerland) to see what most intrigues you. If you decide on the Bernese Oberland, you might want to consider Lauterbrunnen, Wengen, or Murren rather than Interlaken, but again, it really depends on what you want to see and do.

Hope that helps!

Days 8-12 you should spend the time in the Bernese Oberland, but not Interlaken. Choose from Grindelwald or Wengen or a combination of both.This is Switzerland! It will be a long day getting there,main train changes in Milan and Spiez. Days 13-15 stay in Luzern. As mentioned the Zurich airport is a 70 min train ride.