I played En Los Trigales for my Grade 8 (UK system), which was ok, but then heard the Zapateado from from the 3 Spanish Pieces and was captivated. Unperturbed by the obviously impossible scale passages, I had a go. It was probably a bad idea. The rest of the piece is ok, although it is clear the composer wanted lot of the piece slurred rather than arpeggiated, as I first thought, which makes it harder. But, like many pieces by Rodrigo, a short section ruins an otherwise great piece by making accessible only to people who make a living out of the instrument (and certainly not all of those).
The other 2 of those pieces are perhaps a little better, but both have some fast triplet semiquavers that move around the fingerboard a lot, so will require a lot of work. The 2nd piece starts ok, but the last section (although not particularly fast) does involve some fairly horrific 3 vs. 2 action on the right hand. My teacher at the time told me not to bother with Rodrigo, with the exception of the Fantasia, where you can go a little easy on the last movement without loss of effect- and you need at least a piano to play with. Others said, don't worry, the speed will come. It didn't- I got in a Bach rut and then life got in the way.
After 20 years, I've had an internet-facilitated reappraisal of Rodrigo's solo guitar work. Stuff I didn't know was out there from the parochial little music shops in my parochial island nation. Schott's "Music for Guitar" by Rodrigo is a good compilation, although there are some obvious mistakes- like the Fandango, where the fingering is present for certain chords, but not the note!
The slow movements of Sonata Giocoso (not in the compilation) and Triptico are quite playable, although the latter is rather dull.
The Tres pequenas Piezas are great, especially 1 and 3. 1 is easier than En Los Trigales, and has joyful dissonance side of Rodrigo. 2 is probably only worth playing alongside the other 2. 3 is ok, but requires a bit more effort with strumming technique than most are classical guitarists are used to, but is very exciting sounding. Left hand work is fine for all three.
Zarabanda Lejana- the effort is the left hand- no silly scales required. Looks ok.
Pastoral is straightforward, although again, maybe a little dull.
Dos preludios- 1 is charming- not easy, but not silly. 2 is silly, although sadly has some nice sections ruined by the silly hard bits.
Un tiempo fue Italica famosa- as far as I can tell, this is little more than a show piece- the recordings I have heard are technically impressive, but I do not warm to the music at all. Life is too short.
Dos pequenas- the first one is probably just about ok. There are the flying left hand triplets of the 3 Spanish pieces, but these sections are short- and the resolve on single notes, not chords, which helps greatly. The second one is typical Rodrigo- ruins a warm and very playable piece with one bar that appears to have little musical relevance to the rest of the piece. Includes a demi-semi-quaver scale, in the 11th position at crotchet=100. My feeling on this one is to treat the bar as a cadenza, and play it super slow- let him haunt me if he doesn't like it. On the recordings I have heard- the scale is not played at this speed at all.
Finally- the Sonata a la espagnole- after a few plays, I would say is also highly approachable, perhaps easier than En Los Trigales. There are three pieces in this- with the structure quite similar to the 3 pequenas- especially the last piece, which has some wonderful dissonant strumming. The first is marked "castizo", and seems to be played with the main theme as some diluted version of Bartok pizz. Not sure I like that interpretation- we will see how it develops. Suggestions welcome.
And as mentioned by another poster- the Album for Cecilia (transcribed from piano) has some wonderful little tunes- especially the first, which has that addictive perpetual motion feel to it.