I think of both orgeat and grenadine as complex syrups with other stuff in them.
Certainly in the Jerry Thomas era raspberry seemed to be most common but pomegranate syrup in the form of grenadine and orgeat syrup (is that a fruit?) have been more or less common in the prewar era as well. Pineapple syrup not unheard-of and indeed is included in the highly delicious East India.
How do you make pineapple syrup? Is this where you make a thick simple syrup, pour it over pineapple and let the syrup extract the pineapple flavor? That's quite different than the raspberry syrup which is actually make raspberry juice and puree.
Yeah, that seems to be the most common recommended way to make pineapple syrup, though the flavor will fade over time, or did when I made it like that. I think the distinction that makes grenadine not a fruit syrup may be a bit technical, it's used in more or less the same way, and contributes a fruity character to drinks.
Definitions of what is and is not classic are of course a matter of opinion but Don the Beachcomber liked Passion Fruit Syrup quite a bit it seems, and green mint syrup pops up here and again, as well as anisette syrups, mostly in Frenchy Things. Strawberry syrup not exactly a common thing to call for but not unheard-of, either. Apricot and lemon come up in the Savoy.
Any particular syrup you might be looking for a recipe for? Or just determining which ones you want to have?