Be sure to check the glacier access https://www.glaciercountry.co.nz/ as the way to the glacier might be close in the case of bad weather.
An absolute highlight was in the evening the Matheson Lake with mirror reflections of the NZ’s highest peaks Mount Cook and Mount Tasman. There is a ca. 1h30 min return walk to get to the best observation points but it absolutely worth. We stood there for ca one hour at sunset to take photos of the different reflections. Awesome!