That's cool. I also work with teens, and have for about 10 years off and on. The first thing I'd ask you is there a particular theme you're going for?
The song 'Walk On' pretty much speaks for itself as far as being an inspirational song. But U2 songs usually have many layers of that metaphorical onion you can peel back to reveal a deeper meaning.
For any type of drug addiction issues, the song 'Bad' knocks it out of the ballpark. There's a version of it that's on the Boston Elevation DVD. It starts with 'Bad', and goes into a snippet of '40', then into 'Where the Streets Have No Name'. There's a single continuous track of that on one of the 'Electrical Storm' singles, and it doesn't get much better than that one.
Personally, I think one of U2's hidden gems is 'The Playboy Mansion'. That's an onion that you have to peel for a bit before you get to the soul of it. And speaking of soul, 'Beautiful Day' can lift ya up a bit, too.
I also like 'I Still Haven't Found What I'm Looking For', and the version from the Joshua Tree is my 'ISHFWILF' of choice.
Also, you can check out this page on @U2, and it might offer you some help:
http://www.atu2.com:80/lyrics/biblerefs.htmlThere's tons more, but these songs jumped out at me.