<<"Yes I have been thinking of skipping the Rhine Falls(for the same reason you had) and go direct to Stein Am Rhein than (do you mean "then" ?) Rapperswil. Still find tuning the places of interst and not overload ourselves and allow ourselves to enjoy at a leisurely pace.">>
Stein am Rhein has a really nice main square. Loaded with tour groups. I've been there twice. Once in the winter...not so many tourists. Once in the summer. Hard to take pictures due to tourist density. It has good reason to be popular. Very photogenic.
The castle up above has great views and a small restaurant.
We walked up through the vineyards and enjoyed our meal with a view. I don't recall if there is local bus service.
Rapperswil itself has a nice small old town, and the views are nice because of the lake. There is lake boat service.
From Zürich to Stein am Rhein via Schaffhausen takes one hour 20 minutes, more or less. Depending on when you get up in Zürich, you could get there by - for example - 0928 or 0952. Walk around for an hour or hour and 1/2, catch a train to Rapperswil at xx06 for an hour and 40 minutes and have lunch looking at the lake.
Explore Rapperswil, train to Hurden then include the walk from Hurden to Rapperswil (best direction) .
Catch a frequent train back to Zürich from Rapperswil and be back well before dinner time.
You might catch a boat boat from Rapperswil back to Zürich, but I'm not finding the service at the moment.
Or, have lunch at Stein, train to Rapperswil, explore the town and/or take the boardwalk, and take a train back to Zürich.
Those would fill the day but not be rushed, especially since you could skip the castle at Stein, or the walk at Hurden or choose not to spend a lot of time walking around Rapperswil.
It is possible to use secondary train lines from Stein a.R. to Rapperswill via Winterthur, Wil, Wattwil, Uznach. It takes 2 hrs 20 minutes with lots of changes; for example, 1106 to 1327. It is not especially scenic. You pass through pleasant Swiss countryside and hills and small towns. Definitely not tourist country. If you were train buffs, or just wished to ride different routes, I'd suggest that you consider it, but it has no special virtue for you, as far as I can tell, and takes 40 minutes longer.