or spun-out
If you do a Google search for expressions such as "long-spun melody", "long-spun melodies", "long-spun phrases", "long-spun theme", "spun-out melodies", etc., you will in fact find lots of quite convincing examples in classical music reviews written in English. Here are just a couple:
The 18-voice ensemble ... is an ideal number not only to convey the full measure of those extended waves of harmonies, but to sustain the long-spun melodic lines that weave through the supporting chordal structure.
http://www.classicstoday.com/review/review-16292/Long spun melodies, deep harmonies, feather-light percussion, sonorous chord-shifts – the sound of the Abdullah Ibrahim Trio in concert: deep, memorable and moving.
http://www.glasgowcityofmusic.com/assets/0000/5693/Piano_FIN...