Everywhere and anywhere. Take your 3DS with you wherever you go and you might just be surprised!

oh, I live in Scotland btw.
- I've been able to get street passes without even leaving my room (both on-campus and at my parents house) just because someone else will have turned their 3DS on or walked by.
- I get streetpasses whenever I go to uni. Two I'm guaranteed to get (the two friends I usually sit with in class also bring theirs everywhere they go) but sometimes I get more.
- Any busy area! I tend to get some when I go shopping - even if the only place I've gone to is the supermarket! Also, if you're going to be walking past a high school or college campus at a busy time of day they tend to be good areas to pick some up.
- My goldmines are Nintendo zones at a supermarket near my parents house, and then a major train station I go through frequently. I picked up nine at the latter today, then got a tenth sometime between then and getting home from uni.
oh, I live in Scotland btw.