Sitting in a coffee bar in Marylebone High Street - I'm struck by how successful these less than perfect places have become. It is the antithesis of busy - to relax with a coffee - but coffee itself is a stimulant. I gather that in Seattle where the phenomenon was born people started drinking coffee in order to keep themselves awake for working the strange hours that computer programmers keep.
It's also a great place for single people to go to. One does not feel out of place, and in general a coffee bar is quite friendly. Local coffee bars - not the chains in London - can become the focus of local networks. I observed some really nice ones when I was last in Seattle. The locals in the housing neighbourhoods have comfy sofas and always a noticeboard overflowing with local information. The buzz in the morning with joggers coming in for coffee and a muffin and in the afternoon weary moms come in to chat with their friends.