No, but I wish I had it. 
I like the horizontal details.
Go as Jason and final girl.
Of course one of you will have to hold a machete over your head for the entire race…
Personality-wise, we’re down with “just this side of appropriate” or “topical and in poor taste” but there have been some very appealing ideas here.
I just suck at Halloween costume dress up. My mind is always such a blank, but I love seeing the creative ideas people come up with and I wanted to see how the Dope turned its mind to the problem of costume + 6 mile race in PDX.
I was a cat for three or four years in a row as a little girl because I love cats. Boring.
My favorite costume as an adult was Goose from Top Gun (lived in San Diego), weedy little mustache, flight suit, trickle of blood down face from impact with the canopy and all.
I think streaking is out, this race is in PDX after all and we’d like to be somewhat unique. 
Plus, I’d have to hold my boobs the whole time. They’re not big, but they’re too big to be allowed unfettered while running, much as they’d like to snuffle the wind with their little pink noses.
And I’m not fast enough to dress like Jenn Shelton. (Or tan enough.) So WonderWoman underroos might be out.
Little Red Riding Hood & the Big Bad Wolf are promising (and easy prospects). I wouldn’t buy this mask for the run, but it’s gorgeous and perfect. Might make a cheap version. Likewise Alice & the Rabbit, with Alice having the bonus of not having anything capelike. My hair is really very short (1/2" or so) so I’d end up with a wig.
Flying Monkeys is an excellent idea, there will probably be some Dorothies on the course.
A friend suggested the Wonder Twins, which makes me wish dogs were allowed on the course; we could run with Tahoe as the Space Monkey Gleek. I kind of really dislike purple though.
OK, this is just this side of appropriate. Maybe several steps on this side of appropriate.
My wife dresses with a light army helmet liner, camouflage jacket or shirt, grease paint, etc. For her pants, it is only simple black leggings.
I wear Army boots, army pants, canteen etc with a nondescript black shirt.
We each wear a name tag.
Q: What is on the name tags?
Upper G.I. on hers and Lower G.I. on mine!
You could always dress as athletes from other sports. Those clothes are designed for mobility, comfort, etc. A tennis skirt and shirt (with or without a racket strapped to your back) would be very good for running. Also, a gymnast in her leotard (or a dancer for that matter) could work. Basketball jerseys and shorts, baseball jersey and running pants, soccer jerseys, etc. would all work for running. Perhaps the only thing that wouldn’t work is a football player (pads and a helmet would get hot), but a cheerleader would work well.
Perhaps, to tie you two together, you could either go as members of the same team or members of rival teams, perhaps with you being the underdog “chasing” the traditional leader.
For hubby man how about Caster Semenya (link), with a massive “bulge”?
i vote Rocky and Bullwinkle.
Go as peter pan and tinkerbell. Easy to make , just as easy to run in and if anyone asks him who he’s supposed to be he can say robiin hood.
Yeah, premade costumes tend to be pretty cheaply made, but of course, they’re not meant to last more than one night, so it makes sense.
Thank you everyone for all the suggestions…I think I may be very lazy and go the Little Red Riding Hood route, as the skimpy premade costume shop outfit styles lend themselves well to running in, even though it violates the “no capes!” rule. The Man has grey running shorts & pants, so I can make him a big bushy tale and get a mask.
I love the really creative all-out costumes people come up with (like the stormtrooper in Lex87’s link) but I am never very good at planning such things.
Oh c’mon, it’s Portland! You have to do zombies, or pirates, or pirate zombies. Or go as ghost pirate zombies and follow a group dressed up like Scooby Doo and the gang.
Wile E. Coyote and The Roadrunner.
For the Wile E, just need “brown” everywhere (light on the front, dark on the back - long sleeve brown shirt and leggings) and maybe a dog nose-mask. Some long floppy ears with a bit of wire to make them stream out behind you (something like rabbit ears, just color them brown).
http://metrospokane.typepad.com/index/images/2007/09/24/wile_e_coyote_2.gif
For Roadrunner, light blue leggings and long-sleeve shirt, yellow bird nose-mask plus dark blue bandana, bright orange socks and get a little pair of bird wings (like those angel wings that little kids and/or Victoria’s Secret models wear).
Basically both costumes are just long sleeves and leggings - you can get cheap longsleeve wicking shirts at Target (I wear them running all the time) and for tights just put leggings over or under your running shorts. The nose masks will let you breath (or you can just use face makeup instead of an actual mask). Wings and ears should be at toy stores.
Wile E can wear a “sponsored by Acme” sign. Roadrunner can carry a little rubber horn to go “Meep meep!”.
What about some complete non sequitor, like Masai warriors? Then you can have fun making up explanations.
Well, my Grandfather was on the Titanic see, and he was the only surviving member of his lifeboat by the time it bumped up on the shores of Africa, where he was saved by . . .
Valgard, that’s a supercute idea. Definitely going in the workpile.
TruCelt, I’m not tall enough to be Masai. 
Plus, I’d probably get my ticket punched by someone who thought I was making some boneheaded Kenyan/spearchucker “joke.”
Long wig + running shoes* = Lady Godiva.
Or for the pair of you, strategically placed fig leaves for Adam and Eve.
- For comfort, not historical veracity, since the organizers would probably frown on a horse.
Been reading about Bay to Breakers?
Prison uniforms and remember get the police to drop you of at the start of the race
Cool username+thread title combo. But I gather a shell is not a terribly effective costume for running.
Nancarrow, I dunno. This guy did it. And I suppose I could do something more streamlined, less floppy, and it would be appropriate to have The Man dress as a Hare, since he’s generally much faster.
I finally got around to googling for Bay to Breakers costumes, okay, maybe just ogling all teh nekkid. But I am glad to say that this is not an option for either of us.
Ooh, this one wins easiest/most dangerous (for me, the klutz) to run in.
Speaking of klutzes, this is a great picture of costumed “dominoes”–compare the face of the girl in the back to the guy in the front.
And I have no idea what she’s supposed to be, but this is a seriously cute girl.