Ok. First of all, there
are many good band pieces, they're just hidden under masses of crappy middle school arrangements and dumbed-down lameo pieces made for making money for publishers. Here's a good list to follow. Generally, anything on this list will be good:
List of concert band literature - Wikipedia, the free encyclopedia
That said, these are the scores I recomend:
John Barnes Chance: Incantation and Dance
Percy Grainger:
Irish Tune from County Derry, Lincolnshire Posy, Shepherd's Hey, The "Gumsuckers" March
Gustav Holst: First Suite in E-flat, Second Suite in F, Hammersmith
Robert Jager: Esprit De Corps
Joseph Wilcox Jenkins: American Overture for Band
Peter Mennin: Canzona
Darius Milhaud: Suite Francaise
Vaclav Nelhybel: Trittico, Festivo
Ron Nelson: Rocky Point Holiday
Alfred Reed: Armenian Dances (Parts I+II), Russian Christmas Music
William Schuman: George Washington Bridge, New England Triptych
Fisher Tull: Sketches on a Tudor Psalm
Clifton Williams: Symphonic Dances, Fanfare and Allegro
Ralph Vaughan Williams: English Folk Song Suite, Toccata Marziale
Good luck!