We will be flying into Zurich late May and will immediately take the train to Zermatt and spend the night there. We will spend the entire next day there and if the weather is nice will go to Matterhorn, if not, Gornergrat. Question is, we have another night and day to spend and was wondering if we should spend the second night at some other place along the train route back to Zurich or stay in Zermatt. We do not have to be back into Zurich until the third night. Thanks
Give yourself full two days. You really want to maximize your chances of seeing the Matterhorn. It's one of nature's greatest monuments, and it would be a shame if the mountain remained shrowded in fog for the one day you allotted.
Stay the second night in Zermatt as well, and be prepared to spend the better part of the third day as well. The Mattherhon is beautiful, but so are the other peaks. Allowing yourself at least two full days in Zermatt will reduce the weather gamble.