Long before I joined our group, they had gone to a model of monthly Board (Business Meetings) and then only two General Meetings per year. One is held in August to approve the budget; one in May to elect officers. Because of this, our board is deliberately large (25-35 people, depending on how many positions are co-chaired).
I found it very odd at first, but am now a full-fledged convert. It works very well for us.
Great effort is made to promote the idea that the Board meetings are open to anyone who would like to attend. (We want to avoid the reputation of a closed-door clique.) Additionally, we have a PTO newsletter to keep everyone informed.
Currently, our PTO meets monthly. After the first two meetings of the year when we vote on what projects to fund and the budget, the remaining meetings are reporting-out only. We have a large(17-20) member executive board that also meets monthly to handle the day-to-day business plus a monthly newsletter. Because our monthly meetings are short and attendance is low, we are thinking about having fewer meetings. I'm looking for ideas and feedback from other organizations that have reduced the number of meetings. p.s. Our parent involvement is good and fundraisers are well supported. Thanks!