An event in a game does not require us to have a faction there, nor does it require a faction's consent. While we don't have [active] factions in Starcraft, Counter-Strike, Diablo II, Jedi Academy, Unreal Tournament, Halo, among other games, I know for a fact that our members play them and we can indeed organize events there. Anything online and multiplayer. Of course factions are a good place to start (in RS, Guild Wars, Maplestory, WoW, EQ2, GunZ, etc.), but we are not confined to them.
The events can be loosely or broadly organized as well, no need to turn an event into something that's not fun.
Also remember, screenshots are key. Try to take that into consideration and create a spectacle of some sort.

... And lastly, no one is confined to organizing just one single event. Along similar lines, the event organizing is not confined to just the Garden Festival Committee. They are organized to focus on events during the week of the Garden Festival, but that doesn't mean others can't try things as well.
So, I'll leave it open here. I already talked a bit about what I'm planning, now it's your turn.

Let's make the Garden Festival something that's remembered for the life of the guild.