I am a bit confused on the best routing from Zermatt to Venice. My Confusion: which is the way to travel for scenery, which is for quickest route to Venice. We will have the Swiss half fare. Hope someone may have done this routing in the past.
The only practical routing, in my opinion, is through Visp or Brig, then Milan. Travel time 7 hours. Any scenic routing will take much longer and might not fit in a single day.
On that route, you have one option every morning (around 8) with only 1 connection in Brig.
The Swiss Half-Fare Card covers you from Zermatt to Domodossola (the station after Brig). If you pick the routing with only one connection in Brig, you can book it in totality on SBB (Swiss Railways). If you have a connection in Milan, book to Milan Centrale on SBB and on to Venice on Trenitalia (or Italo if they run on that route, I do not remember).