[fadetree]

In VP/TOV, randomize timers, allot days to guilds. Big guilds get their own day, groups of smaller guilds get combo days. No spawn on your day? too bad. Can't kill it all on your day? Oh well, grats next day. 1 day per cycle is free for all. So, if there are 3 top guilds, a, b, and c, and three groups of smaller guilds a1, b1, c1, the cycle would go
a,b,c,a1,b1,c1,open,a,b,c,a1,b1,c1,open. Extra open days inserted as needed to make sure the day of week pattern rotates. Guild grouping for smaller guilds done by CS, and subject to change at their whim.
Guilds earn a spot in a day by completing lesser content or being invited by a guild who has a spot. Days are tradeable. If you are caught breaking day, you lose your next to the folks you barged in on.

Complicated? Yeah. More work for CS/guides, but a wiki/subforum to do the tracking and day trading. All CS has to do is to run scans against zone population and guild memberships, probably could automate. Dropping or changing guild tag takes a cycle to 'clear', i.e., you are still considered to be in your old guild/unguilded for a full cycle after you switch.

Enforced by GM's/guides, but only as far as who can be in zone that day, tactics are open season.

All I can think of, I'm sure its full of holes and has been brought up before.