Go easy on the aromatic bitters (use drops rather than dashes) or your Casablanca will be more orange than "blanca". Original recipes in The New American...
Do try using a red cherry liqueur (I used Merlet Sæurs Cerises) instead of the clear Luxardo Maraschino liqueur as some Casablanca recipes suggest.
I compared the two following the recipe here (though omitting the sugar syrup) and preferred the red one having a more full filling taste. I do find the White Lady much more interesting than the clear Casablanca. Maybe I would like the clear Casablanca better, if swapping Bacardi Carta Blanca with Plantation 3 stars, but that be cheating or?
Following Andrew's suggestion, omitted the sugar syrup and it was quite sweet enough. Perfectly balanced with the nice flavours of the rum. Very interesting blend to tastes. Very good.
I tried this for the first time today - stonkingly good (but then I am a lover of Aviations and White Ladies). I don't think it needs the sugar to be honest.
Simon, Casablanca also gave us ‘round up the usual suspects’.