Spend Less Time On Design, More Time On Spirit
A great community spirit can overcome a terrible community design.
A great community design can't overcome a terrible community spirit.
When you're planning your online community, spend the bulk of your time planning how you're going to develop a great community spirit (not a great community website).
You get a great community spirit by doing things that bond a community. You need to give members real control over your community. Solicit personal contributions. Plan group events. Document the community history. Highlight in-jokes and milestone moments. Create content about the community.
The goal is to create a feeling (not a place) that your members are in it together. Nail this, and you've nailed the delicate art of creating a community.