Personally, I like YYYY/MM/DD, but it hasn't caught on (anywhere).
As far as metrics, the US tried, at least back in the (*ahem*) 70s/80s. I was only taught metrics in grade school... I still don't know standard measures very well because they were never taught, nor metrics because they were never used.
I have my handy-dandy standard-measures-conversion-table posted on the refrigerator to this day, if I need it!