I used to all about Pepsi, but I've noticed that once Coke gets flat, it tastes far superior. Unfortunately, that does not happen often enough. I just drink my soda too fast.

Ice helps, but then sometimes there's the situation with a paper cup from a fast food joint, that if you leave the Coke in too long, at the bottom, there develops this sort of fine film that you drink, and it collects on your tongue. It scrapes off into something disturbingly similar to chewing tobacco.