Hi SDhets -
I just checked and realized that I don't know when you are traveling.
It does make a difference in the Alps.
So, if you last day is not on a Summer Saturday or Sunday ( many many many too many tourists) I'd suggest Stein am Rhein ( minus the trip to the castle unless you can figure out how to get up there with your child ) .
The 7 year old would find interesting things at Technoprama in Winterthur, but it is not particularly Swiss....just a nice science museum:
en.wikipedia.org/wiki/ Swiss_Science_Center_T echnorama
<<"think I would settle for Rigi as have heard of Titlis as very busy and difficult to navigate a pram/stroller around in cable cars,etc.. On a separate note, is it advisable to take a pram/stroller for mountain trips or just take a baby carrier?
The hike from Lauterbrunnen to Stechelberg looks exciting but is this Hike fine to take a Pram along with us well? I may as well add this to my Itinerary for things to do in Lauterbrunnen.">>>
The Rigi is the "tamest" and most suitable for strollers or prams, because of the variety of trails or walking areas.. If you take a stroller, make sure it is foldable to fit easily in the small train cars.
The path along the valley floor from Lauterbrunnen to Stechelberg is easy and nearly level. although iot does slope up gradually toward Stechelberg.. I've not walked it, but I think it would e suitable for a tram or stroller.. The trail follows a back road and path which parallels the main road. ( In yellow on the map with the hiking trails turned on.
map.geo.admin.ch/?topic=ech&lang=en&bgLa yer=ch.swisstopo.pixel karte-farbe&layers=ch.bav.ha ltestellen-oev,ch.swisstopo.swiss tlm3d-wanderwege&layers_visi bility=false,true&E=26 35955.00&N=1157145.00& zoom=7
Your comments on rail passes seem reasonable, but I let the moderators comment. They keep up with the details of passes.