I've also thought it would be cool to do some sort of organized PVP, particularly if it involves the sort good spirit that RPers can bring, or that you can get with intra-guild events.
I think all of these sound like a lot of fun. I would probably lean toward your versions of Capture the Flag or Huttball. I would probably suggest doing it on Ilum, as that is usually totally dead, and there's less chance of griefers interfering. Granted, Outlaw's Den is pretty dead as well, but you still periodically get people who show up there that might disrupt attempts at organized event.
I had actually considered trying to organize something like this on a smaller scale as a guild event, except in my Yavin stronghold, and using the Huttball decoration, and perhaps Revanite Altars as goalposts. :) I thought the Huttball decoration, given its random explodiness, could add a fun level of chaos. I was thinking that it could play very much as you would expect, with the person carrying the ball trying to get across the goal post (alive), with the added benefit that the decoration allows you to pass the pall to other people on your team. What was missing here was testing exactly what sort of PVP flagging is permitted in the Yavin SH, something which I never had enough people online (and from opposing factions) at the same time to do. I don't suppose anyone else has tested what sorts of flagging are permitted there?