2 days to spare in Switzerland after Bernese Oberland vacation

Hi. My wife and I will be in Switzerland for about 10 days with our toddler. This is our second trip to Switzerland and we really enjoyed our stay in Bernese Oberland area last time around, and therefore we are dedicating 8 days in Wengen and Grindelwald area and plan to make day trips to nearby places like Murren etc. We fly out of Zurich but have 2.5 more days still left in our itinerary. We already covered Lucerne in our last trip so our not so keen on going back there. Similarly, Zurich attractions don't catch our fancy as much. We really like small towns and nature walks, and not so much the big city feel. Looking for suggestions on the best way for us to spend our last 2.5 days. Some ideas that we are playing around with include the Heidiland & Liechtenstein Tour but the tour reviews don't make a very compelling impression. We may also spend a few hours in Stein am Rhein but that may only take a few hours based on my research. Would a trip to Black Forest area be recommended (no car though!)? We would really appreciate any ideas/tips. Thanks!