>> I should start by introducing myself: I will be visiting Switzerland in the second week of April for the first time with my wife and 13 year old daughter. I am myself am a railway fan and have a model train layout (I have a model of a Ce 6/8 Crocodile among others)….
… Our plan is to spend 5 days and see the alps (and for me to ride a variety of trains).
… April 8: Arrive in Zürich from the US. Take train to Chur and spend the night there.
In keeping with your wish to ride a variety of trains, if one of the departure times suits you, you might like to do this sector on a Railjet train. The Railjet is an Austrian train, and it runs on the route between Hungary, Austria and Switzerland. Railjet services (identified in the SBB timetable as RJ) leave Zürich at 6:40 am, 10:40 am and then every 2 hours until 18:40. You would change to an urban S-Bahn train at Sargans for the final 20 minutes to Chur.
>> April 9: Take Glacier express Brig and then BLS to Spiez on the classic route (not the new basis tunnel) as I wish to travel over the famous Bietschtal bridge.
Apart from the Glacier express, would it be interesting to take a RhB local train and change in Disentis/Muster to an MGB
Yes, you could do that: take a Rhätische Bahn train to Disentis/Mustér, a Matterhorn-Gotthard Bahn train to Brig, then the Lötschberger to Spiez. Taking these local trains along the Glacier Express route will usually involve a change of trains in Andermatt as well as Disentis/Mustér. If I remember rightly, there is no raised platform at Andermatt, so that might make it a little more awkward if you are travelling with luggage. I’ve always travelled that sector luggage-free, so I’m not 100% sure.
However, it would be a shame to miss out on the offical Glacier Express train! The Glacier Express doesn’t leave Chur until 11:26 though, so you would get into Spiez much later than if you took the regional trains.
>> April 12: Morning cruise on Thunersee,travel to Zürich and stay near the Hbf
Your boat travel will be in the direction towards Interlaken West, I presume? (No morning services in the other direction).
I don’t know what aspects of trains interest you, but many of the services from Interlaken West/Spiez/Thun to Zürich have a family coach with play area. I’m not suggesting this for your daughter, as she is far too old ;-D, but it is interesting to see one if you have never seen one before. The trains with this feature are identified in the SBB timeable by “FA” in bold italics. There is more information here:
>> I will be buying 8 day passes. It appears that I do not have to buy a separate pass for my daughter (is this right?).
She’s 13, so that’s right, as long as you also get a free Swiss Family Card when you order your Swiss Travel Passes (or else get it at a staffed railway station in Switzerland by showing them your Swiss Travel Pass).