The square is a great place for the Christmas market or any of the other events that occur there throughout the year! It is a convenient walk from Maidan; about 10 minutes (depending on the route you take, you will arrive at St. Michael’s Monastery first).
The view of Kyiv from the St. Sophia Bell tower is well worth the entrance fee. The nearby Hyatt has a rooftop bar that is a tremendous place to spend a spring or summer evening.
I would recommend visiting the area while walking Khreshatyk and Maidan.