> correspondence set in Calibri looks like something dispatched from a leasing office

In general this is the way I feel about anything written in a Microsoft-, Apple-, or Ubuntu-supplied typeface. If you stick to system fonts you the pinnacle of embodiment of apathy in my book.

Have some backbone, browse through Google fonts, pick something that represents your organization and stick with it.

Even if you are a leasing office, pick a good font. That will make me more likely to lease from you because your attention to typography conveys to me that you will also be attentive to details in building maintainence. If you communicate in Times New Roman and Arial it tells me that you probably are apathetic about mold in the walls and electrical code as well.