We have a committee for each event. Sometimes the committee is just two people, sometimes it is 5 or 6 people. I have listed some of the standard committees below:
Fundraising-puts together fundraisers
Awards-handles quarterly grading period awards for students
Hospitality-meets, greets, handles refreshments at meetings
Staff Appreciation-organizes things like Staff Appreciation Week, weekly snacks for staff
Red Ribbon Week-Drug Free week in October
BoxTops-is responsible for the collection, counting, and mailing of General Mills Box Tops
Recycling-responsible for collection and redemption of empty ink cartridges, old cell phones, aluminum cans, etc.
Volunteer Organization-does phone work, usually contacting voluteers to work events, to Thank volunteers for their time, puts together the volunteer log, etc.
I think those are pretty basic. I know I've forgotten a few, but you get the gest of it. Toss in actual events like Santa Shop, Pioneer Days, Spirit Wear, etc. and that pretty much sums our group up. Most of the rest of the stuff is handled by our board of officers as a group, our executive officers as a group, or our membership as a group.
I don't think that 'more' is better necessrily, or that 'less' is better. I think that each group puts together what they need, and each group has different needs. Our officers oversee each group. If that is how you plan to do it, make sure that your officers are able to cope with the number of groups they will oversee.
Good Luck!