According to your way of being you are able to conceive any travel plan, of course.
A slower travel shedule does not help your wish to do it all. Switzerland is an wonderful, amazing country - that is the truth. Having that short period time , early spring, you can do a lot of trips, yet. If you decided to be independent travelers then pick-up a sort of card or pass and let's turn on the lights!!! On www.sbb.ch are shown the timetables, routes, maps, distances, times for every machinery created by the human being - trains, cable-cars, boats, buses, chair-lifts, telegondolas - it is a chance to plan the smartest trip, having THE MAP in front of you.
How did I do it? I wandered like un UFO across the country, being so happy to have the opportunity to see and live such a marvel. I am from a poor, former communist country, we had not the opportunity to get over the Iron Curtain during our youth.
I was in Liechtenstein and in so called Heidiland. My opinion about Liechtenstein is : waist of time. For Heidiland I was coming from Bernina route, get off the train at Flums, pick- up the bus to Flumserberg and stayed there 2 nights, almoust 3 days. It looks like in the pictures, I guess is wonderful in every season, you can get a lot of cable cars around and move beyond all the mountains till Unterzen - Wallensee Lake where I took the train onward. In August, having full sunny days all the time. I'd go by my own from Luzern to Heidiland , dawn to dusk, knowing the weather report for that day.
I tried to squeeze the orange till the last drop, this is a verry expensive country, to have a good accomodation how we want to is almoust double than in other West European countries, so....
My best regards!