I have a pretty unique set of wants for this year's spring play, so here we go:

-About 10 actors (our musical this year has 25 actors, and that's just too much for one director)
-Most of those parts should be girls.  4 guys, tops.
-I'd like it to be something in two acts- at least enough to fill an evening.  Last year I picked a show that looked like it would be long enough, but once we got it up to speed, it was only about an hour without the intermission.
-No "one scene and done" characters unless that actor can double somewhere else.
-If the show has a chorus, the chorus should be interspersed throughout the show (our play last year had a significant chorus with named characters in the first scene... and then they never appeared again.  The rest of the show used an almost completely different cast of characters, but not different enough to fully double Wizard of Oz style.  I ended up writing a scene into the second act so they had a reason to be on stage).
-Nothing inappropriate for a relatively conservative director- I don't even want to have to edit if I can help it... the kids have started a tradition of keeping my edits up until the final performance where they conveniently "forget."
-Limited scene changes.  Our stage was built cheaply in the 60's, so we have about 5-6 feet of wings and backstage area.  Not a lot of room for fancy set changes.  We need either something static on stage or minimal that can be implied with basic stage dressing and lights.  Scene changes between acts/during intermission might be okay.

OTHER CONSIDERATIONS, BUT OPTIONAL:
-The kids really like comedy, but every play for the last X number of years at this school has been a comedy.  I'd like to slowly transition to something with a little more meat.  So maybe a good dramatic comedy or action adventure or romantic comedy or something along those lines...
-Period costuming is a challenge due to our limited budget and small costume closet (or more accurately, a completely full costume closet that looks more suited for a thrift store or garage sale than a theatre... you know what I mean)
-I've been itching to get some stage combat involved, particularly some sword fights (I know this almost certainly requires period costumes, but oh well)

I also have a play that might work.  Tiny Tim Runs the Marathon, which may also be produced as Run Like the Dickens, has a cast of 9+.  It's a comedy, but I think a fairly intelligent one, and it has some opportunities for combat.  In a few lines:

Media darling Oliver Twist has gone from a lowly orphan to an anxiety-ridden corporate spokesperson, pitching everything from juicers to cereal and tofu by reenacting his days in the workhouse and subsequent adventures. But Oliver's monopoly on the inspirational rags-to-riches story is threatened when Tiny Tim throws aside his crutches and decides to run the marathon. Tiny Tim has the chance to inspire millions, but with a homicidal trio of fairytale princesses, scheming Corporate Mommy and Daddy, and meddling friends and family, Tiny Tim may not make it to the starting line.

http://www.playscripts.com/play.php3?playid=2055

I'd also recommend a pair of plays at YouthPLAYS.com.  First is Love (Awkwardly) by John Rotondo and Maryann Carolan:

Eight juniors and seniors navigate the wonderful, painful, exhilarating and awkward minefield of high school relationships and the moments that matter the most: the first kiss, flirting, dating, breaking up, going to college and what goes through their heads as they sit in the most boring class ever... (8-14 actors, and there's a little combat sequence in this one too)

http://youthplays.com/plays/view/183/Love_Awkwardly

And if you can go a little bigger, Lockdown by Julia Edwards (15 actors):

When the doors of the CliffNotes Library suddenly lock down and someone hears a gunshot (he thinks), a motley crew of students and one freaked out substitute teacher must rise about the social chaos to save a life—and maybe learn a little about tolerance along the way.

http://youthplays.com/plays/view/192/Lockdown

Cheers,
Jon

I was very impressed with "Rabbit Hole" , done by a high school in Iowa... One of the most powerful, yet humorous, plays I've seen in my career...

 Just MHO, but an hour show is about right, at least for my audience and casts.   Might have to look into rabbit hole...