I just can´t find "my" repertoire, and although this questions popped up here already plenty of times, I would appreciate your help on finding once more some good repertoire literature for somebody/me!
So, please let me specify as much as possible in detail what I am looking for:
I aim to beautifully play piano at a certain level (level 6 or 7 on a scale from 0 to 10). I am now playing level 4, and hope to have in 1 year a good grasp of level 5. Levels 6 might then be another 2 years, and level 7, who knows if I will ever reach it. I for sure will not have time to train hard enough to reach any higher level.
Thus, I on the long run will build up my personal library with pieces of level 4 to level 7, and therefore ask you for proper literature recommendations:

- I rank myself at the moment to play "SMP level 4 to 5" (according to preview pages of sheet music sold at sheetmusicplus.com); I am practicing at the moment Burgmüller´s "Arabesque", Beethoven´s "Für Elise" (complete), Schumann´s "Träumerei", Beethoven´s "Mondscheinsonate" ("Moonlight Sonate") (1. movement only), and will for sure be busy at this level for the next 6 month.

- I search for repertoire series/collections/books covering melodic and dreamy music from classic, romantic and impressionism.

- Original piano pieces shall only appear in their original version, but not as simplified arrangements.

- Arrangements of beautiful or famous pieces, which have NOT been originally written for piano are very welcome as well, but those books should then NOT mix much original piano music in, but clearly stay focused on original none-piano pieces.

- I much prefer editions which inform for each piece about the technical skills the pianist is recommended to especially keep an eye on: I am very satisfied with the book "Romantic Piano Anthology Vol. 1 Grades 1-2" by Nils Franke, which is organized in a graded way, provide short but beautifully melodic and short pieces: I for sure will follow this series, and also go for the other anthologies of this series. But I still search for much(!) more pieces!

What can you recommend me?
I placed the same thread also on the ABF forum...

Try Helen Malais' "Succeeding With the Masters" series. The books incorporate useful analysis and technical instruction, from Intermediate through advanced levels.

Actually, I think you mean Festival Collection by Marlais. The method books have the title you suggested and would be too low a level for the OP.

I think you will enjoy Satie's Gymnopodies and Gnossiennes.

I think you're confusing Succeeding at the Piano (method books) with Succeeding with the Masters (repertoire books). I am a big fan of both series. Helen Marlais is a superior editor and her editorial suggestions are quite useful.

I'd like to offer a suggestion from PianoWorld composer, ScottM (Scott Aaron Miller).

He's composed a set of 7 preludes for piano, which are simply wonderful in my opinion (-humble...).

I'm attaching 3 videos with myself performing 3 of the preludes (No.1, No.5 and No.7).

http://www.youtube.com/watch?v=py9GZ_hRQY4
http://www.youtube.com/watch?v=gmEU6wqOzoM
and
http://www.youtube.com/watch?v=nmw1quwNFwM

I think that the works are rather dreamy (and quite mystical) on the edge of impressionism, with some romantic elements. Preludes No.6 is a homage to Rameau so...

I'd say that in terms of level this book would be around 5-7 levels... Not too difficult in technical terms, but probably a bit tricky in musical terms.

I should also note that there's no fingerings in the score. Me and Scott decided against putting fingerings, since it is rather advanced music, plus fingerings can be very personal, and as such we opted out.

No. Perhaps you are referring to "Succeeding at the Piano" which is the new method from Helen Marlais, starting with prep until Level 4 or so, at this point anyway. Still coming out with new books. But she also has "Succeeding with the Masters", which progresses to Early Advanced levels. The "Festival Collections" coordinate with the "Masters" series. Please take another look. (HelenMarlais.com/succeeding

Thank you everybody very much for the recommendations,
especially to point me to "The FJH Music Company Inc", which publishes "Succeeding with the Masters". I actually haven´t heard about them before. The "Succeeding with the Masters" perfectly fit my needs to get presented graded repertoire with each piece being well introduced / commented! This is exactly what I was searching for, something being very similar to the "...Piano Anthology..." by Nils Franke which I knew already. Comments and introduction to the pieces seem to be even much more detailed, than Franke provides them. The "Festical Collection" would then provide more pieces, carefully chosen to never duplicate repertoire which was already presented in the "Succeeding with the Masters", but this time not commenting the pieces. So, I might start with the "Succeeding with the Masters" and learn from it, and afterwards could just add repertoire to my personal collection by adding the "Festival Collection" to my repertoire. Again, thanks a lot!!!

Well, on my search for a "dreamy" music collection I meanwhile also found something fitting my interest. I could by youtube already confirm that each single piece in the following publication would please me and waiting for the delivery of my sheets and of a CD, which is separately also available: "Just Beautiful - Piano, Thirty Sumptuous Slow Piano Solos Chosen" by Kevin Mayhew. I will have to work for advancing with my skills, though. Seems, that unfortunately for my current level, there are not many pieces composed for. If you would know more publications featuring this style of music like done in this collection, still let me know!
Best wishes, and many thanks to all of you, Marco.