Thanks for the email.
New room's are cool, aren't they! I think the best thing you can do is make the room reflect your purpose. (I'll assume your youth group has a purpose- I talk a little about this in my planning article,
or you can read excellant material on this in Doug Fields book "Purpose Driven Youth Ministry."
For example- if you purpose is: "The goal of our student ministry is to expose teenagers to God’s love, to equip them to exalt God, enjoy other believers, and experience the work of the ministry."
Then I might decorate a whole wall with "EXPOSE TEENAGERS TO GOD'S LOVE." Have that title on the wall in big letters. Post pictures from outreach events, kids coming to Christ, Gospel illustrations, the flyers of upcoming outreach events, etc. Then decorate another wall with EXALT GOD! Pictures of your worship service, kids raising their hands together, an information sheet on your student led worship service, etc.
The room will have a fun feel, but more than that, it will REEK of your ministry. Anyone walking in will see exactly what your ministry is about.
Hope that helps.