Try to visit on a week-day rather than during week-end -- less people, less foot traffic, less distraction to you from playing the pianos!

They may or may not be able to show you, but ask to see the "Piano Bank." That's a big room in the basement where they store their fleet of C&A concert grands, probably more than a dozen of them in one room. Those are supplied/rented to visiting pianists who want to perform in the area.
If you go to Steinway Hall, might as well visit Faust-Harrison Pianos, Broadway Pianos, and Klavierhaus -- all virtually on the same block (205~211 West 58th Street), about 5 minutes walk from Steinway Hall.
https://www.klavierhaus.com/ -- go check out the Faziolis
https://www.broadwaypianos.com/ -- go check out the Shigerus
https://www.faustharrisonpianos.com -- go check out the Mason and Hamlins
Have fun!