There will never be a case when everyone is happy, either with a schedule or even a choice of who coordinates campaign timing.
Before I go further, I would like to point out the obvious, if unintended, bias toward large campaign design/hosting groups. GFL was barely mentioned above. SFC2.net and SFCX are getting a lot of press, but they aren't, and shouldn't be, the only places to look for campaigns. Frankly, I think there are many issues at play, some of them old biases for or against EAW or OP, or biases for or against certain individuals or groups. If possible, we should shove those all aside before they become flame bait in a well-intentioned discussion.
First, no one "official" schedule needs to be created, though posted schedules would certainly help the players and admins as a frame of reference. There also is no need for a committee. All we really need is a line of open communication for any campaign hosts/admins to coordinate with each other. An forum may or may not serve that purpose, since they tend to lend themselves to flamefests.
I am not a part of the SFC admin mailing list, but I understand a lot of good information sharing has taken place there over the years (it's been THAT long??!!). Perhaps that list, or a scheduling mailing list, would serve the purpose of keeping lines of communication open. The way to subscribe to it should be easily accessible so any new admins or old ones who want to start coordinating plans can join the conversation.
The key is NOT championing the creation of time-block schedule that essentially dictates when admins can run campaigns, or how long they have to wait for a chance. For one thing, the fewer simultaneous campaigns available, the less inviting the game is for new or returning players. Old hands have their favorites, but even they like a change of pace now and then, sometimes on a whim.
Perhaps what we need are MORE campaigns, but less overlap for the kinds that are very similar in scope, size, and rules/goals. So, if an admin decides they'd like to run a small-map, short-run campaign with specific VCs and a custom shiplist, they won't feel like they have no opportunity while a big-map, long-term campaign with long-running team planning and role-play is rolling along. Do people get my general point here? By overdoing the scheduling, we are effectively killing variety and player choices, which also diminishes creativity in design. Even if Campaign X gets 15 players at prime-time vs. Campaign Y's 30 and Campaign Z's 5, they can all still be fun and offer players a range of options.
So, how about trying to let the communication happen, let the schedule be free-flowing, allowing late entries and overlap when campaigns aren't very similar in design? I think the admin groups and individuals could benefit from being kept up on each other's plans so they don't step on toes. I know the players would benefit if they didn't have to choose between one "serious" campaign and one or more "fun" campaigns (still a poor term, I must say). I'd rather have the tough choice of spending my hours on 2-3 campaigns I like than having no place to play if I don't like the setup of the current offering(s).