In college when I learned about degrees Kelvin, I realized that Fahrenheit is the better, more precise measurement. And now I live that every day. ...Live, knowing that Fahrenheit is superior, but having to use Celsius. I don't really know if Celsius is technically "metric", but they seem linked.
The WHOLE WORLD uses Metric. With the exceptions of Myanmar - a screwed up military regime which, let's face it, has very little credibility, Liberia - a tiny African nation which was founded by American President Monroe, and of course, the good ol' USA.
I'm guessing the only reason we didn't join the rest of the world in going metric is because we're big enough that we don't have to. Think of the headaches and financial loss to have to change EVERYTHING we use, across the board!
Here are things that have messed with me in China, by being metric when I was not prepared for it:
1. Bed linens. No "queen, king, double..." How many cm? We decided our bed is about as wide as a queen, but a few cm short.
2. Measuring cups & spoons. Seriously! Do you know how many ml in a cup? I found some empirical measuring cups for my own recipes.
3. Paper. Click "print" in any document. We use A4 - which is about 8.28" x 11.8". My computer still defaults to empirical units, so I have to switch it over each time. Oh, it would print anyway, but I prefer to see an accurate pre-print image. This one item: paper - impacts EVERYTHING - planner pages, notebooks, posters, mail, file folders, banker boxes...
4. Picture frames. I brought several lovely 9x13 prints with me, determined that I need to look for frames in 23x31, BUT the closest I can find are 21x30. So I had to trim the pictures anyway.
Those are just a few odd things I noticed, apart from when my students asked me how tall I was, and looked blank when I said 5'10". 178cm gets a big reaction, though.
I think in terms of Celsius now. I speak in Celsius. I don't do a fancy conversion in my head, but over 30 is hot, 25 is nice weather, 15 is getting cold, etc. This beer can says "5*C-25*C". 25*C is ridiculously warm for beer, in my American opinion! But, that's usually how they drink it.
Kilometers still throw me off. Then again, even State-side, I judge distance by time more often than by miles. Fortunately, I don't drive anywhere.