For this, I'd have a "Going to see Gran" context, because it sounds like you consciously know, when leaving the house for that trip, that you're going to see her. Of course, then you might need to have a "check relevant Going to See... lists" item in your Travel checklist, to remember to check that list.
Originally Posted by cfoley
For the USB-stick friend, though, it sounds like you would see him on smaller occasions that wouldn't have an associated checklist? If you see him in person, you could have a "Joe in person" context, but by then, it's presumably too late.