Another building that we don't have a separate button for is Hotel. It currently uses the same button as Salon. I cropped down the Civ5 Hotel to make this one. Civ5 icons are pretty good, but they are round, not square, so only a few of them can survive being cut down (to the point where adding the frame covers the corners).
View attachment 403350
View attachment 403350

to the corner.
icon.
could work better.