My favorite dreams are when I compose music in my dreams - my usual dreams only rarely involve fully conscious control but in these musical dreams I can do things I only wish I could do when awake. eg. I can't play/think multiple real sounding instruments playing simultanously but in the dream that kind of arrangement decisions can be made what feels "realtime" while the composition is evolving constantly.

The most annoying part is that I remember no details at all of the music when I wake up eventually.