well it the only criterion is "good," you might like:
Relato + Relato Sans

However, i'm sure it would be more helpful to hear how you are going to use the type. Check the Design Forum Read Me for ideas of what types of information might be useful in helping us to make suggestions.

If you want something more extreme you could try Zalamander for a teenager-look.

Just a though: when I was a teen (not that many years ago) any attempt by anti-drug / sexual health / eat your veggies groups to be cool was decidedly un-cool. I think that appealing to the older end of your spectrum (at least design-wise) would be a good idea, since teens are always trying to act older than they are.

Also, teens are very cliquey - the hip hop kids don't associate with the emo kids. Depending on what group you want to target, the design aesthetic will change. My suggestion is to look at popular album covers and try to replicate the look of Snoop Dogg or whomever the kids are listening to these days.

- Lex

Paul, It will most prominently be used to establish a word mark and then used for titles on posters and other material. It won't be used for body copy, if that helps.

Lex, that's a good idea, thanks.

I've seen Fedra & Fedra sans looking very fresh and non-stuffy in a magazine layout.

Circa 1985:
"Well, kids these days like the band Poison. Let's use Hot Pink on Black and use a really Xtreme typeface! Then we can get a Longhaar wearing lipstick to pitch for us. The kids will dig it."

Circa 1995:
"Well, kids these days like the band Nirvana. Let's use a really Grungey typeface and get a depressed looking Longhaar wearing flannel to pitch for us. The kids will dig it!"

Circa 2005:
"Well kids these days like that Snoopy Dog rap guy. Let's use a graffiti typeface and get a really menacing looking black man to pitch for us. The kids will dig it!"

Lesson?

DON'T BASE YOUR DESIGN ON CURRENT FADS IN POPULAR MUSIC.
(Sorry Lex...)

If your message is serious, then make the design appropriately. The last thing we need to see more of is an AIDS ad with graffiti and a menacing looking black man saying that we should practice safe sex just because someone thinks that Snoop Dogg is cool.

Choose typefaces and and designs that clearly communicate YOUR message, not someone else's.

Dan - you're right - I've become what I hated the most - THE MAN! (And not in the "you da man" sense either).

"Yo, home boys - I think Snoopy Dogg is off the hizzy, yo. Don't be wack - use a condom, 'aight?"

- Lex

Maybe my freebie Autostyler could work? It gives some sort of cute look, but maybe that could be just what you want in this occasion?

http://autodidakt.se/index.php?page=autostyler

If not, I recommend you to take a look at other “boldish & roundish” fonts, even scripts that are bold and round, as I think they are great for the purpose.

Lex:
I didn't want to come down on you so hard, but it had to be done ;)

jselig:
As to the original question, I would use this as an opportunity to purchase a well designed typeface that makes sense as an investment for later projects.

I would consider some timeless workhorses like Avenir or Gotham for sans.

How about Dolly from Underware as a serif?

I'm going to jump on the "don't go trendy" bandwagon. You'll just create something that looks like it was churned out by a grownup trying to look cool. You'll be much better off to come up with a strong concept that appeals to teens and then pick fonts that work with the concept. I think that's why the ”Truth” anti-tobacco ads work so well; they don't at all resemble most advertising that targets teens.

If teenagers smell condescension they will rebel.

Goran...wow! That's a wonderful face. And for free!? That's mighty nice of you!

Omnes - adds informality/curves as it gets fatter. Would be useful long beyond this initial campaign.

http://vllg.com/JoshuaDarden/Omnes/mudTyper+Weights/

... and the italic is GORGEOUS!! (Omnes)

Goran…wow! That’s a wonderful face. And for free!? That’s mighty nice of you!

Thanks, I’m glad you like it. It’s my christmas present to the world :)

well, many thanks from the world then! And good job with the site too.

Make your own font out of colored condoms.

I saw an ad on the bus this morning:

A black and white photo of feet sticking out from under a blanket with a toe tag hanging from them. The copy (in Helvetica bold condensed) read "Get a life: GANG LIFE is a DEAD END".

It wasn't trying to be cool or anything, but I can't see many Snoopy-Dog-listening gang members seeing this on the side of the bus and realising that they've been wasting their life.

"A dead end? Dang, yo. I'm a enroll in law school or some shizzle."

- Lex

lol@ lex.

Yes Omnes is quite nice and I'll keep it in the 'potential' list.

Also, I think some of the 'trendier' campaigns are not really concerned with longevity, they just want something that appeals 'this year'. My favourite is the new (RED) campaign for AIDS, aside from that I have to agree that everything else is pretty played.

The demographics don't lend well to using scripts, as part of it won't even appear in standard English alphabet languages.