Codeine and caffeine. The reason for this weird choice is that they're both weak in their respective departments, but still strong enough to do the job most of the time. I can't take caffeine daily, nor do I crave it - I enjoy it around 5 times per month and when I do drink coffee, I tend to like the experience.
Codeine, while weak, still gives me that nice warm euphoria and relaxation most of the time. I like the sedation as well, as opposed to the more stimulating opioids.