At sit down restaurants, I have noticed that even if the restaurant is totally empty, the hosts/hostesses, always put you near other people. I remember once, there was a huge party of little kids and there were very loud, and the hostess put us in the same area as they were and the whole restaurant was empty. She did move us when we asked her to though.
I have noticed that if there are several seats on the bus, but no seats where people can sit by themselves (wherever they sit, they are going to sit beside someone), people will always end up sitting next to me. When this happens, it's usually a woman. My mom said that women sometimes feel more comfortable sitting next to other females rather than males on public transit. So maybe that's why? Still, there are other women on the train.
I am probably more of an "overly smiley" aspie rather than a "grumpy-looking" or "blank expression" aspie. Everyone says that I smile a lot. Maybe people sit next to me because I am a happy-looking person?