Any dark or black rum works well in a Dark and Stormy, which is just a good dark rum and a tangy ginger beer. I like Reed’s Ginger Brew in my D&S. We mixed up two pitchers at last night’s New Year’s party and they were a big hit.
Something I just kinda spontaneously remembered–back in college, we used to make our rum & cokes with dark rum (Gosling’s black seal, I think). It worked out pretty well.
I find Gosling’s Black Seal to be a fine sipping rum, as well.
(I rarely mix anything, but a nice Dark & Stormy goes well in the sunner.)
I have rum. I have ginger beer. I have an unsuspecting boy who gets off work early tomorrow. I will report back with results! 
(Thanks a bunch, y’all - birthday shopping is going to be easier this year, and we’ll have some interesting new things to try in the meantime!)