One of the things that I've started coming across recently as I browse through higher-difficulty solos for Alto Sax is that a precious few of them actually have a melody. True, that is a broad statement, but some of the ones I can think of that are melodically beautiful are the Creston Sonata, Tableaux de Provence, Desenclos' Prelude, Cadence et Finale, and Concertino da Camera. I mean, seriously, could you hum the tune to any part of the Denisov Sonata or of Bolcom's Lilith? With that, what are some good solos that are beautiful melodically and harmonically, or that, basically, have a good tune?
The Dressel Partita is a beautiful piece. Very romantic in its harmonies...and uses the altissimo register very fluidly, which adds to the challenge. It is in five movements, but mvt 1,2 and 5 are a common selection in performance.