This may be a stretch piece, but there's a Ralph Ford arrangement of Wizard of Oz that has four movements. I've done it with our 1C Middle school group several times when I was the JH director. If I only had a brain can feature tuba if I remember correctly, and there's some nice flute moments. I can't remember baritone parts on it. The nice thing is it is four short movements, so you can always do less than the four!

Over the rainbow was one of my favorites to do with the 8th grade parents.