The question https://music.stackexchange.com/questions/615/pieces-on-the-same-level-as-sarabande-in-d-minor is asking for
other classical and famous pieces are on par with this one, so I will know what to learn to play next
and further specifies to
give me a rough indication of the difficulty of the piece i.e what grade piano it is considered
I'm afraid this will result into a lot of questions of the type "Can you recommend similar music for X?". However, we aren't building a recommendation community as far as I understand...
I think the intent can be saved though, by creating a wiki of a list of learning music of different difficulties.
What do you think?