Schubert's D.960 sonata (Molto Moderato) clocks at 21 minutes, with Richter's notorious performance at 25+ minutes, including all repeats. The opening movement of Schuber's String Quintet is 20+ minutes, depending if the repeats were observed, while his String Quartet no. 15 is even longer!
Mahler and Bruckner have huge opening movements too.. Is that "heavenly length"?
Post some of the loooonnggeest movements in this thread. Do you like them?