* meters
* kg
* lean celsius but don't care too much either way
* abolish seasonal time changes
* for online calls/events specify time in UTC
* YYYY-MM-DD date format
* ground floor is 0th; don't skip 4 and 13
* don't put sugar in cold tea

Simple rules for a civilized society.

some good suggestions. What are your thoughts on mph and km per hour. I don't tend to mind that one too much.

Hello from the Basque Country /drip-haus @artwithhumans
Not Financial Advice 

I'd like to know if mph and temp/height measurements in the USA now have more of a nostalgic effect. I studied nursing (RN) in Australia and one of the interesting and sad case studies we read was about an error made from the confusion of measurements between the two countries.

km/h is better, better to dump miles entirely imo

Though for fuel economy I prefer (distance unit) / (fuel quantity) rather than the reverse; that's the one good thing that MPG has over the Canadian standard (L per 100km)