When I was living at a hospital while my son was in ICU for a month, I used to streetpass some medical professionals every day.
Over time, I became to know where they would be, or at least where their 3DS would be at certain times. I ended up meeting a couple doctors, one was an anesthesiologist, that I kept streetpassing. Also, one of the my son's respiratory therapists was a regular.
That hospital was the biggest hotbed of streetpasses that i have ever come across other than Disney World.
You see the depths of my heart and You love me the same - Indescribable