I'm sorry I don't understand I have a series of useful phrases from Jukuu, that assist learners in developing conversations and learning new word/phrases. Which of these would be more appropriate for talking to a stranger?  Would I choose a different phrase for a doctor or for a family member? If other phrases are more appropriate please let me know.

謝謝！

Will you speak a little more slowly?
请你说得再慢一点，好吗?

I am sorry, sir. Can you repeat that more slowly, please?
对不起，请你再说慢点。

I'm sorry, can you repeat that.
对不起，您能重复一下吗？

A: Can you repeat that, please?
甲：请您再说一遍好吗?

Sorry, I don't understand.
对不起，我没明白。


EDIT: To clarify this question. Please note that I am looking for the situation where one would use one phrase rather than another.

Examples might be:

Use phrase x when talking to family members (etc.)
Both five sentences above will be used under talking with strangers rather than people who you actually know. These are very polite expression and are in most case inter-changeable. However, it will be odd to talk to someone who you have already known with that level of politeness. It might work for Professor(s) / leader(s). Talking with friends or family will use more colloquial expression like

"稍微慢一点" "等一下，你说得太快了"