Cash: Who doesn't love cash? As Monty Python once sang "there is nothing quite as beautiful as cash" - and they should know following their recently sold-out one-off revival gig.
Fiat, fungible and fun - cash makes the ideal gift (with card or simply stuffed in an envelope) for teen relations who you never talk to. However, be careful to set a standardised gifting limit or risk being 'unliked' on social media.
Also, useful in coin form, stored in piggy-bank to cheaply fob off children aged eight and under.
Bitcoin: For those who don't love cash. Hard to wrap, even harder to understand, buy a Bitcoin for your cool, digital-era relations. As they won't be at the family gathering anyway, you won't have to worry about the Bitcoin price volatility spoiling the Christmas day good cheer. Complement with USB stick.
Gold: For those who hate cash. Last year half a bar might've been all you could afford but gold is going cheap this season and the full bar might be within budget. Perfect for the miserable pessimists in your gift circle (you know who they are).
Bury it under the tree.