Aw, don't feel so bad. At least you've got one more orchestral work under your belt!
My piece,
Journey to the Oasis, runs 6:40 long, and the scene is a man's journey across a desert. Each section in the piece depicts a specific part of his journey - encountering a mirage, crossing a high dune and seeing a vast desertscape before him, and other such landmarks. Since I had the scene vividly in my mind, I guess you could say there are cues. You could certainly animate or shoot a scene to go behind it. However, it is also very suitable for the concert hall, standing as a piece in it's own right.
I have several flute solos, one rather nice solo for viola, and the saxes and clarinets get some time in the sun. I treated the saxes as horns, since the horn range is larger and the GPO doesn't have a sax patch. I used the piano for incidental coloristic effects, nothing soloistic.
The piece begins in the key of G minor and wanders in and out of some nice tonicizations. Near the end, there's a temporary modulation to C major which quickly turns back to G minor, and then the final chords are heard in C major again. Thus, my timpani are pitched to the G on the bottom line, and the C above that. The snare drum is heard quite a bit during the "walking" sequences, which are rather lumbering and weary-sounding.
Once the competition ends, you'll get to hear my piece and find out how the story ends!
...You know, if you want to bother rescoring your thing a little, and Thomas doesn't mind, you could transfer the horn and trombone parts to the saxophones, and drop the tuba unless the basses can somehow pick it up. Transcription's always an option. I understand we're past the deadline, though - shame you didn't notice this a little sooner, eh?