Hike across a wooden walkway to the Hurden Peninsula. Or take a boat trip on Lake Zurich. Visit Knie's Children's Zoo. Or simply explore the old town on a walking tour.
On the Planggenstock you do not have exactly the same beautiful view of the Walensee as from the Hirzli. But otherwise it is just as beautiful and on the Planggenstock …
There is no restaurant up here, and consequently no good kitchen, as Werner already wrote. The little climbing up here is worthwhile because of the view.