Itinerary Re- Visit

I posted a tentative itinerary here a few weeks back and got some great feedback- Thanks to everyone who responded. Here is the current plan some tweaks. We are comfortable with this pace of movement, want to do some scenic rail trips, and will take some day trips along the way.
We purchased the Swiss Travel Pass when it was on sale before the Holidays. We are both 65 and like easy 4-5 mile hikes.
This is our first post retirement trip with the luxury of time but we still want to allocate our days and our budget well!
Day 1- Arrive Zurich, train to Lucerne
Day 2- Lucerne
Day 3- Lucerne
Day 4- Lucerne- one Lucerne day will be a possible day trip to Bern
Day 5- Golden Pass to Berner Oberland area, sleep Murren
Day 6- Murren
Day 7- Murren
Day 8- Murren
Day 9- Murren
Day 10- Golden Pass to Vevey, Partly for the train ride itself, partly to see some of the area
Day 11- Vevey
Day 12- Vevey
Day 13- Train to Zermatt
Day 14- Zermatt
Day 15- Train to Milan. Our only one night stay is planned here- but we need it as a transit connection and we want to see the Last Supper. Plus, Hilton points will give the credit card a little break!
Day 16- Train to Varenna
Day 17- Varenna
Day 18- Varenna
Day 19 Bernina Express to Pontresina
Day 20- Pontresina
Day 21- Pontresina
Day 22- Complete Bernina Express Route to Chur, then on to Zurich
Day 23- Flight Home
Any and all feedback is appreciated!