I just recently found a really dreamy Chopin work to play, his Berceuse, Op. 57. Sitting there at the piano you just start to fall into this lovely dreamland that I often feel is reserved for Chopin only. Not a Beethoven’s Moonlight Sonata dreamland (which seems to me to demand your attention to the picture it paints), nor the Schubert/Mendelssohn lieder dreams where listening to choral versions sends chills up and down the spine. This is the sort of dreamland where you simply float in an endless feeling of not quite wanting to do anything but let the music wash over you.
Often, Chopin sticks these kinds of dreamlands in the middle of some work when you least expect it, as in the famous Fantasie-Impromptu, where he stops the rollicking ride for a little rainbow chasing ;). The nocturnes often do this as well.
Are there any other classical pieces that take you to dream land? Your thoughts, please, while I think about how fun it is to play chromatic minor third scales for two-and-a-half octaves. 