His two drinks of choice were, yes, Martinis (gin, natch), but not "Bourbon Orange Blossoms," a drink that doesn't really exist. You may have been relying on William Seale's history "The President's House," [I was] but he makes a mistake in describing the bourbon and orange drink that FDR would make. FDR's favorite drink (even above the Martini) was the Old Fashioned, which is made with bourbon or rye, sugar, bitters, and (optionally) muddled orange slices and a cherry. FDR included orange slices, and instead of muddling, he would squeeze the orange slice into each glass. Thus Seale's confusion—he must have looked up what a drink with orange juice was, and found the Orange Blossom (a Prohibition drink of gin and orange juice) and then assumed that what FDR was making was an Orange Blossom with bourbon, and thus called it a Bourbon Orange Blossom.