High quality ingredients is what will elevate this sundae float (what should probably be renamed a "milkshake") from just okay to utterly divine. Made one with good instant coffee and Hershey's brand cocoa powder and syrup and it was okay. Made another "Chocolate Sundae Float" last night, opting for very cold, full-fat milk, the darkest and ripest banana I had been saving specifically for this purpose (seriously near rotten), Callebaut Cocoa Powder, Ghirardelli Sweet Ground Chocolate Sauce, Haagen Daz Vanilla and I must say it was well worth the trouble! Excuse me for being so adamant about this but one really shouldn't call this a "float." Floats have something that floats, like a big scoop of ice cream on top. If nothing floats, it isn't a float. As a long time chef and all around dessert enthusiast, I'm a stickler for calling things by name. Anyway, nice, easy dessert. Cinnamon, would be overkill. I say go dark or semisweet for some real chocolate kick and yes, use the blackest, most overripe banana you can for real banana flavor.

A milkshake is an ice cream drink that is processed in a blender. But a "Float" is a drink that has an intact scoop or two of ice cream on top which is normally served over soda. Soda floats come from the times of the Soda Jerk or Soda Fountain shops of a bygone era. They started as a sideline in pharmacies where the druggist had the equipment to formulate them in the 1920s.
For sure, you should always use the best ingredients you can afford.