Hi CBS, maybe you should add a poll to gauge the responses. This can be found just above your post to the right "Add a poll".
Of the four options I’d say the lid would be best. Mainly because its right in front of your face before you take a sip. As for the stick not everyone would use one, no sugar usually means no stir. Metal plate, I know I never hold the bottom of the cup... Temp indicator on the side sounds ok too, but thats only if the customer looks at it. All the best :)