My impression of your post is that you intend to have multiple presentations, as in, "Sit down and listen."
People might be more receptive to more of a "fair" type open house. Maybe tables with different aspects of what you do. That way, your could interact more with the visitors. If I were to attend an open house for a guild, I would want to get a "feel" for the people in the guild. I'd like to know more about what I can get out of it. We're all selfish. If we spend our time with a group, we want to know, "What's in it for me?". Is it mostly a social thing? Am I going to improve my quilting skills? Are the projects that the guild takes on going to gratify my sense of community? Is this mainly a sales opportunity for long-armers?
I'm not a member of a guild. I'm in a large city with a large "all-purpose" guild and a modern guild. I believe that all the suburbs have guilds as well. Although I sometimes attend their quilt shows, I've never attended a meeting. One of the suburban guilds is close to me (if they have a quilt show, I don't know about it). I've considered attending a meeting to see what it's about. However, their website is not up to date, I don't do Facebook or Twitter and nothing has really spurred me to go.
Had the employee at the now closed Hancock's Fabrics not told me about this suburban guild, I would not have known it existed. She gave me a laminated bookmark with the guild information on it. The background printing is a grandmother's flower garden in orange gingham.
bkay
Another thought..... for refreshments, I would suggest cookies and a couple of drink options - maybe coffee and bottled water or hot tea, if this is to happen in the winter. Keep it simple. Also, put your most gregarious member on the refreshments table. Remind your members to talk with the visitors, not each other.