Six days trip in February

Hi,
I plan the following train trip in Switzerland, starting February 1st. I have been to most areas before.
February 1st arrive in Zurich at 11am, train to Luzern and boat to Vitznau, walk, rest
February 2nd, Sunday- Rigi ( maybe leave that afternoon to Interlaken?)
February 3 Luzern to Interlaken express and on to Zermatt ( or morning in Interlaken, if arrived on Sunday evening)
February 4th- Zermatt and train to Brig ( mostly because hotel price in Zermatt is so high, and also to make it a shorter ride the next day)
February 5 - Glacier express from Brig, or Zermatt to Chur or St. Moritz ( I have never been to both. Hotel I Chur is cheaper, but not sure what to decide)
February 6th- Bernina express from Chur or from Pontresina ( I think no train from St Moritz, if I read the time table correctly). If I go to St. Moritz, I could walk around and spend the night in Pontresina,,also walk around in the morning before the train at 10am.
I have a lot of questions and hope you can help.
Thank you!