One thing that didn't come across/wasn't discussed is that you can divide Bitcoins into smaller parts.
I think we need to move to mBTC before folk begin to understand this.
A guy at my work didn't understand this either and he's a programmer like me. He assumed that they could only be moved in whole units and didn't understand how that would work if its a currency. When I explained it can be divided to 8dp, and that could be changed in the future he was like "ahhhhhhh that makes a lot more sense"
we had an invitation to a major german venture capital company to present a bitcoin business idea. they had no clue what bitcoin was. so we started to explain it. when it came to the "there will only be 21 million btc ever existing" thing, they said that no economy can be built on just 21 mio pieces. we tried hard to tell them about divisibility. they did not buy it. they asked questions like " but who is setting what divisibility comes in place, who is controlling it ?"
I think what is important for lay people to understand is there are no obvious flaws in bitcoin. If they think they see an obvious flaw or some way in which it won't work, it is important that they understand that they don't understand it yet. This is difficult without insulting peoples intelligence, but I find if you let them 'save face' by explaining the underlying system is only really understood by cryptologists and mathematicians, they dont feel so dumb and resistant to something they don't get straight away. This gives them the time to absorb it.