Here's the thing. In my direct experience, amateur CG players almost invariably try to play pieces well beyond their grade level. Someone who might be able to give a very passable rendition of "Lagrima", instead tries "Capricho Arabe". Someone who could play Ponce's "Tres Canciones" reasonably well instead chooses (with their teacher's full connivance!) to inflict "Theme Varie et Final" on the audience. And so forth.
I leaned MY lesson years ago, and I simply don't try to play anything past about Grade V levels. My own Damascus Moment came from reading a 1939 interview in "The New Yorker" with the famed German pianist Wilhelm Bachaus. He said "Why seek difficulty when there is so much that is quite as beautiful and yet not difficult? Why try to make a bouquet of oak trees, when the ground is covered with exquisite wildflowers?" And Bachaus possessed a true virtuoso technique, so that things like the Beethoven piano sonatas, Liszt's "Don Juan" Fantasy, the Brahms-Paganini variations, and so forth were his standard concert fare. And there is no doubting whatsoever that the CG repertoire is overflowing with such "exquisite wildflowers" ready to be plucked (in BOTH senses of the verb!)
These are wise words here and I am on the same page with my playing and aspirations. Rather than torture myself for weeks trying to play a grade 7 or 8 piece (that I end up not being able to play with a high degree of security), it's far preferable to learn a grade 5 or 6 piece. They are usually close to being sight-readable and come together quickly, meaning the process is fun. Once learned, I can play them securely.
I am always on the look out for 'wildflowers' up to grade 5 or 6. Obviously there's stuff like various Sor studies, the Brouwer studies, Pavlovits, Yvonne Bloor, various Carcassi and Carulli studies, Peter Nuttall, various Tarrega pieces and Sagreras..
Feel free to point me to any other stand outs in this grade range, good tips appreciated.