I was in Stockholm last week and used mostly plastic. Very convenient!

1. kr leftover from trip 2+ years ago.
2. Found out that my kr50 bill was no good and was told to use my kr100 bill because its shelf-life was time limited. Same for my coins - Gyros shop in Södermalm helped me with that.
3. In a bar in Kungsholmen, I used my change - see above - to buy beer and the bartender had a look of "huh - change? What the heck is this?" It seemed as if he had a nice laugh to himself because of the tourist using (soon to expire) coins.

Cheers