In terms of BTC, I think you should gift them no less than BTC0.10. 1 tenth of a bitcoin is small, but enough to make people understand they have a fair portion of a full coin. If you give them something less it will feel insignificant. People using fiat aren't familiar working with or realizing the value of less than a tenth of basic denomination, e.g., no one sees value in having 7 cents, but a dime or more is something.

Now the challenge is that a tenth of a bitcoin is roughly $60 right now, not a cheap gift! But you could wow them with the amount of things they can buy with just a tenth of a bitcoin.