I think it probably really depends on the co-working space. I was at one for a few months that made a point of socializing. They had a portion of space dedicated to meetups from 7pm. They had 4-5 meetups a week. They organized dinner outings. One person organized a programmer meet up where he'd give out a short problem, have everyone solve it in their language of choice, then we'd have each person explain their solution, it was enlightening so see why each person made their choices.

I don't know how to know beforehand if a co-working space has lots of social activities or not, maybe see if they have an event page or a FB page showing past events.