I still really want Phantom to tackle Liszt's most famous symphonic poem, Les préludes. Prometheus, Orpheus and Mazeppa would also work on the field if arranged well.
And speaking of Strauss, we never hear much of his music on the field outside of the opening of Also Sprach Zarathustra. I really want to hear more. Alpensinfonie, Tod und Verklarung, Feierlicher Einzug... So much of his (instrumental) music has that expansive, brassy content I just love hearing on the field. Not to mention this underrated opera intermezzo that would make a perfect ballad: