How many days for Astana?

I bought an open jaw ticket with arrival in Astana as part of a 2-week self-guided trip. I chose Astana as the entry point into Central Asia because I was fascinated with its odd architecture, and it seemed like a nice place to just "be" for a few days. However, now that I've been learning more about Astana, I'm questioning my choice. Astana doesn't seem all that interesting or even an easy place to just chill for a few days, with the large distances between places in the city.

Though I could change the arrival city for a fee, my inclination is to just keep Astana as my first destination in Central Asia and figure out the right number of days there. For those who have been there, what would you recommend? I could spend 1, 2, or 3 days in Astana, with 1 day being the arrival day (I arrive early in the morning so it would be a full day).