Two senior citizens will be in Zurich for two days in late March, 2019. what are your recommendations for activities? Thanks so much.
You can opt to stay in the city of Lucerne which is near Zurich, 45 minutes from Zurich airport. There are more activities to do there.
https://arzotravels.com/things-to-do-in-3-wonderful-days-in-lucerne/
https://www.thecrazytourist.com/15-best-things-lucerne-switzerland/
I couldn't agree more with RJean. Luzern is a wonderful city. You could do it on a day trip, but I'd recommend staying there. It is situated on a river with beautiful and famous bridges, and its on a large, pretty lake. And its surrounded by mountains. What's not to like? ;) You can take an excursion on the lake to a cog railroad up to the top of the mountain. Luzern isn't a cheap city, but likely more cost effective than Zurich if that might be a deciding factor. Other options might be day trips to Bern and Basel, but as nice as those cities are, I feel Luzern has them beat by far.
Yes, don't stay in Zürich, stay in Luzern.
That gives you a nice town to explore, boat trips on the lake and local mountains to go up (Rigi, Pilatus and Titlis).
See this panorama of Luzern to tempt you: http://tour.luzern.com/360/en/
I would also recommend Lucerne. We were there last March. I would recommend getting the Lucerne pass. I think they have a winter rate and is good for nearly everything in Lucerne. We went to Titlis, Rigi, Interlaken and a few boat rides all for free with the pass.