Anyway, to the question at hand. SBB charges 12 CHF per day to store a bag not exceeding 25 kg (55 lb). So that is about 72 CHF per bag. There may be less expensive services, like bagbnb, but I don't know of any off hand. Luggage is held at Travel Centers at major train stations like Zurich Hbf. It will save a lot if can mange to consolidate all the used clothing in one bag and keep it less than 55 lb. Maybe take a little less for the cruise.
May 8 is a Sunday, so I will assume you are flying home the following Saturday May 14.
May 8: train to Zurich Hbf, allow 1 hour to store luggage, then take one of the many direct trains per hour to Chur. Night in Chur.
May 8: Glacier Express to Brig. Seat reservation required. At Brig, travel on to Lauterbrunnen (or Wengen or Muerren). Get extra credit if you take an added 30 minutes and travel by the more scenic route to Spiez on the "Loetschberger" regional train that uses the old Loetschberg Tunnel rather than the new base tunnel. Stay 3 nights there in the Berner Oberland
May 11: Train to Luzern. Scenic train over the pass goes every hour from Interlaken Ost and has no reservation requirements. Stay 2 nights in Luzern.
May 13: Train to Zurich Hbf and retrieve luggage and spend the night in Zurich.
May 14: Quick train ride to the airport and fly home.
I hear that SBB will offer a 6 day pass next year. Right now they are 3, 4, 8, or 15 only. With a 6 day, you just have to buy an inexpensive airport ticket for the 7th day.
