My husband and I are in our mid-70's and finally going to Switzerland. We will be joining a cruise in the spring, leaving from Barcelona. Would you please suggest the best things to do and see before we catch the ship? We're planning to fly to Zurich and then go to Lucerne the next day. I think going on either the Bernina Express or the Glacier Express would be fun. I'm considering Lake Como and then maybe going to Milan to catch a flight to Barcelona. Scenery and quaint towns mean more to me than museums, but I'm willing to listen to your advice. Thank you!
Going through the question in reverse order:
Flight from Milan, definately possible and makes sense because the train ride is far more difficult than it should be. But watch the details when comparing flights, Milan has three airports and the low cost carriers may be from Linate or Bergamo, not the main Malpensa. Also read baggage conditions/fees carefully. Bergamo is a nice little city, but the flights from there are likely to have the most "hidden" extra fees.
Lake Como, east side works with your plan. How you leave depends on which airport as this is the point where the routes will split, which is one reaon to find the flights first. But arrival is very easy by Bernina Express, which ends at the Italian town of Tirano next to the regional trains which run along the east side of Lake Como. Bellagio or the other side of the lake would be less easy.
The full length Bernina Express ride begins in Chur, the breakfast time departure would probably be best but would require you to stay the previous night in Chur. This little city has an old centre which is good for wandering around. https://www.rhb.ch/en/panoramic-journeys/bernina-express/
The Zurich and Luzern parts needs a little more explanation. Did you have something planned? If Zurich was just a "get over jet lag" stop don't bother, the extra onward journey is only 40-50 minutes. If you have ideas for Luzern then go straight there, direct trains take 70 minutes and run once or twice each hour. Swap the Zurich night for Chur after Luzern. That transfer can be very scenic as long as you use the marginally slower route using the Voralpen Express as far as Pfäffikon SZ.