As one of the founders of the hackerspace you've visited out in seattle & a fellow recurser that you might've heard about the space from, I can drop to you some of my notes & learnings from two years in of devhack.
the biggest piece of advice by far that I pulled from a bunch of european-style hackerspaces (& HacDC, my formative hackspace) has been: Just do it. Find a physical space, start doing meetups, promote it a bit and cool folks will find you.
https://fahrplan.events.ccc.de/congress/2007/Fahrplan/attach...
We at devhack took a very word-of-mouth based approach to promotion and that has prevented what a lot of comments here are trying to mitigate in terms of attracting the wrong crowd too quickly -- although I think there's lots of value in creating a space which supports eccentric folks / ppl with diverse backgrounds.
Founding a hackspace is a very learn-as-you-go experience, has been very fulfilling and has had plenty of hiccups that we've had to react to as they come. The most important part is to have fun and create a fun space for you and your friends.
Also, put a roller rink in your space. very important and wish we had that