Suggestions for an "unconventional" young adult party playlist?

I've volunteered to DJ for my friend's party this year, and I'm quickly finding that composing the playlist is quite greater a challenge than composing the private Halloween playlists I've had for the last few years. Though I'm using a good bit of the same material as I usually would, I'm taking into mind that most of the party guests will be juniors and seniors from the private Christian high school we attend, whose faculty typically look down on the celebration of Halloween (even participating in a church "trunk-or-treat" would probably be considered iffy). In addition, I've learned from attending other class parties that not many of the potential guests have a great deal of pop music literacy, so I'd like to take the opportunity to broaden their horizons.

In an intentional effort to keep the music from becoming too out of sync with the mood of the party (and to maximize the guests' listening experience), I'm dividing the playlist into four segments, each containing songs that complement each other in tempo and mood.

Segment 1 (arrival; exploring the grounds; anticipatory chatter) - I'm trying for a blend of ambient scene-setters (using a lot of Tangerine Dream) and upbeat alternative or indie songs that "scream" (no pun intended) Halloween, like Concrete Blonde's "Bloodletting." This will probably be when guests are busy taking it all in and offering compliments to the hostess, decorators, et al., so I'd like to include a few particularly attention-grabbing songs here to send a few compliments my way, just in case it doesn't happen later in the night.

Segment 2 (icebreakers if any and main meal) - Lightheartedness is key here. Folks who don't know each other will probably still be getting acquainted, so I'm hoping slightly jesting songs with sing-along choruses like Jonathan Coulton's "Re: Your Brains" will serve as fun conversation pieces. This is also where I'll stick most of my oldies, such as "Werewolves of London" and "Bad Moon Rising," as well as sit-down dinner fare like Imogen Heap's cover of "Spooky."

Segment 3 (dancing; games; costume contest; general merriment) - For the heart of the party, I'm simply looking for songs with a strong beat. These could very well be new releases by artists who aren't quite household names but are getting there, like Eels ("Fresh Blood") or Ladytron ("I'm Not Scared"). They should be danceable but not "booming" enough to distract from game instructions or costume contest results.

Segment 4 (wind-down) - These will most likely be mid-tempo songs playing as guests are posing for photos, being handed favors, and reflecting on the evening. Probably the most diverse set as far as style is concerned, it might begin by easing guests out of dance mode with The Who's "Boris the Spider" and concluding with The Postmarks' reflective "Every Day Is Halloween."

Any and all suggestions you may have would be greatly appreciated.