Feb 10, 2016 - 3:49 PM
You can spend as many hours up at Kleine Scheidegg as you like. You can take short look at the views, but there are some restaurants and bars, so may also sit down, have coffee or lunch and take all the time you want. The Swiss Travel Pass allows free traveling up to Wengen/Grindelwald and indeed a 25% discount on the remaining leg to Kleine Scheidegg.
Traveling to Zermatt would be too much in your schedule. A boat trip over Lake Thun could work on March 24 (depending the rest of your plans of course).