Ok I've ignored most posts in this topic. Here is my large dump of what I think are easy pieces (skipping the super obscure ones):
- the posthumous Waltz, in A minor
- the Mazurka op. 34 no. 3 in C major
- the POSTHUMOUS nocturne in C minor (just so you don't end up playing op. 48 no. 1 haha)
- the nocturne op. 37 no. 1 (G minor; a little challenging though)
- the nocturne op. 32 no. 1 (B major; a little challenging though)
- the Mazurka op. 7 no. 1 in B-flat major
- the posthumous Polonaise in G minor
- the C# minor nocturne (has some challenges though- polyrhythms and scales)
- the Eb major nocturne (also a little challenging)
- the E minor nocturne (has some complex polyrhythms)
- out of the Preludes: nos. 2 (needs stretches, and hard to memorize) 4, 7, 15, 20
- Etude op. 25 no. 2 (you have to have a decent technique to play this in tempo though)
I agree though that you should pick up some books with more diverse repertoire. I'd recommend Keith Snell's books in levels; each level has a book for Classical, Romantic/20th Century, and Etudes.
I think that Etudes shouldn't be considered "easy." His hardest etudes, such as 25/6 and 25/11, are probably the last Chopin pieces you should master.
His nocturne-like preludes, such as 28/13 or 28/15, are easier than the majority of his preludes, but you should master Chopin's easiest pieces before you go to the preludes.
His nocturnes are nowhere near easy. 32/1 was rated a Grade 8 by ABRSM and 37/1 requires lots of challenges. The c minor Nocturne (not 48/1) is actually fairly easy, but you should master his Cantabile before you start playing his Nocturne. The 48/1 isn't actually that complicated compared to his ballades and scherzos, but Chopin's ballades and scherzos are his ballades and scherzos, so yeah.
Lots of this mazurkas and waltzes are doable for intermediate pianists. Lots of pieces from the Op.67/68 sets are fairly easy. 67/1 and 68/1 are a bit harder and require a bit more technique, but otherwise, both sets are pretty easy. The Op.7 set is fairly easy. 7/1 and 7/5 are the easiest IMO of the set. The Op.56 and Op.59 mazurkas are IMO Chopin's hardest mazurkas and they should be doable after 1-2 years of playing Chopin.
And btw, there are two E-Flat nocturnes. 55/2 demands some technique and is a bit challenging, while 9/2 is similar to his Cantabile. And there are 3 c# nocturnes, the Nocturne Oubliee discovered recently.