Four of us (active retirees) are taking a train tour of Switzerland in early June 2022. It goes counterclockwise from Zurich, but it skips the Grindewald area. The tour ends in Lucerne, and IF it isn't too complicated or exorbitantly expensive, we'd like to extend the trip by at least 2 more days so we could go up the Jungfrau ("Top of Europe") and the Schilthorn.
Main Question....How difficult (and expensive?) would it be to get ourselves from Lucerne to this area AND then get back to the Zurich Airport without having to drive? Would we be seeing "more of the same" or is this area quite different from the areas we will see on the train trip (St. Moritz, Lake Maggiore, Zermatt, Lake Geneva, Lucerne)?
(Sidenote: Is it likely that Grindewald would have a lot of wildflowers in early June, or is that too early? What about the waterfalls?)
I imagine some would say that we should do the whole thing on our own, but we have credit we need to use from a trip that was cancelled due to COVID-19... so we are just looking for advice about a possible add-on if we "bailed out" after our 2 nights in Lucerne and got ourselves to the Grindewald area and then back to Zurich Airport a couple days later.
Thanks, in advance, for your help!