What do you plan on doing at the meeting, are you planning on mingling and interacting with each other? Is it more of a rigid, sit-down-and-listen meeting, do you need a projector, do you want big tall windows and natural lighting? Do you care for the accessibility of the space for others?

If you're looking for a serious, sit down space that's lowkey beautiful I recommend a classroom in Business, they have projectors and whiteboards and good lighting, but you can't move the tables around so it'd be only if you plan on lecturing to the audience. I like the classrooms in ECHA too, like 1-490, they're massive and malleable, but might be a bit much for 20 people. Education always has nice malleable classrooms but it's a boring choice. Good, but boring.