When you are forming your organization, carefully consider your goals and priorities, as this will guide how your organization (and physical network) grow.
Wireless mesh networks can serve many purposes. What are the most important to your organization? Do you want to give free Internet to the people who cannot afford it? Do you want just to play with technology? Do you want to build a alternative/robust network so that some communication channels will be open also in the case of censorship or other (natural) disasters? Do you want to cover open spaces (parks and so on) for people to have access to the network/Internet while they are mobile? Do you want to cover rural areas? City areas? Do you want to cover as much area as possible or to make it as fast as possible (mesh vs. point-to-point)? Do you want to have an emphasis on connectivity (larger coverage) or throughput (faster).
How will you finance everything? Donations? Everybody will participate with their own hardware? Will you sell some services/premium bandwidth to cover other costs? Will you sell technical support? Quality of service? Do you want to grow fast (probably need to have money) or are you willing to grow slowly, but be strictly non-commercial?
These are all decisions that your organization will have to make. Of course things are not black-and-white, so you don't need to have one rigid answer to each of these questions. Instead, think about these questions, and your priorities, as you grow your organization and network. Of course, along the way, you will get some opportunities for your less-prioritized ideas.