The first "matrix" post was actually distracting. I can l like groups of pictures but not so many at once ... maybe just 4 or so per group. Singly, I thought they were much more effective as viewed in series.
I personally like the combination of humorous photos, portraits and 1) in Ron's list but I feel that the more graphical ones really doesn't fit in as well here like #12 or #20. People and faces specially is really what makes this set strong.
I have some time and I'm sure all of this will change when I start putting things in order and really start thinking about the space they''ll be in...And I'm still shooting and I might pull some back in that I have already tossed out.
There are a few that don't follow theme. To me the theme is as you mentioned "spontaneous relationships" and most follow it, and the ones that are harder to pick out become more interesting as you see the photos in succession. Since at the point of hitting them, you kinda know what to look out for.
So I think the only advice I can offer is figure out the flow. If it were me, I'd start with the more obvious ones, get progressively harder, then finish off with the ones that are obvious but really make one walk away smiling.
Again, there are a few in there that I don't think fit, or are to hard for me to see the relationship of. But that's personal choice, and I wouldn't want to influence you to much so I won't comment on them individually.
Overall really quite neat, and yes ideally you'd display them in a gallery where the flow forces people to go in the direction you want them to go in. Oh and they look better displayed together if you're showing on web.
Really enjoyed looking through this set and spotting the not so obvious relationships. Some crackers in there too that required not just a sharp eye but fast reactions as well !