The piece mentioned, "La fille aux cheveux de Lin," is truly beautiful, and I once spent quite a bit of time learning it, years ago. Not sure I ever made a success out of it -- e.g., up to tempo, etc.
One aspect of that Prelude that daunts me, it has the key with either 5 or 6 flats, (trying to recall) and in addition, the score is peppered with many accidentals of various kinds.
Key signature from hell? (Humor)
For a highly skilled musician, this should be no problem. For me, it is a problem, because I am continually struggling to keep the black keys separate from the white keys.
But the piece is beautiful, not too long, and rewards the effort.
I would suggest the Chopin Waltz, Op. 34, No. 2. It is manageable at your level of skill, and I think you will love the sound -- especially the second melody where he goes over to a major key. As with most of Chopin, there's great need for the pianist to interpret -- just hitting all the notes is not enough. This adds to the fun.
Another really nice piece at about this difficulty level is Ravel's "Pavane for a Dead Princess." Absolutely beautiful.
Best luck--