Trying to put together a 40k Combat Patrol league at the FLGS

I've been blathering about it for something like a year now, and I'm making a big effort to get said league off the ground in 2010. The guiding document will be the 2009 Adepticon rules/scenarios packet, since they were kind enough to extend permission for me to use said resource when I contacted them. I've been waffling and waffling on which army I'll field for this event, rotating through basically every Warhammer 40,000 army I've got minis for (which is an embarrassingly large number of them for someone who's never played more than half of a demo game multiple years ago). Having said that, I think I'll be putting together three lists: one for me to field as my 'official' league entrant, and two as opfors and/or if anyone else wants to get in on the tourney and doesn't have an army of their own as of yet (based off Britt's offer of his teams to people in the Blood Bowl leagues he's run, hint hint Chris this is basically aimed at suckering you into at least playing, if not collecting).

For my actual list I think I'll be running some Orks (a decision almost entirely precipitated by finding out they finally made plastic gretchin that don't cost a fortune), putting together a nice little low-model-count Chaos Daemons list for opfor #1, and still deciding between Eldar, Traitor Guard, and Chaos Space Marines for opfor #2. At the moment I've got tentative responses from a handful of players - Alton has mentioned bringing some Black Templars, Britt actually has (and is therefore I guess not really tentative) Sisters of Battle, there are two possible Tyranid entrants, and Brad is (I think) still looking at some sort of possible list, maybe some sort of combo Guard/SM list from one of the older Inquisition codexes?

EDIT: while it's implied by the nature of a blog, I am of course soliciting suggestions as to which of the three potential second opfors I should put together. Show your work!