Why too easy? It's certainly not a pushover at least, there is an awkward crossrhythms passage for the right hand at one point.
Well try:
Reflet dans l'eau - it's not so hard, you need good TO technique to play the arpegs well, but the difficult part of the piece is relatively short
L'Isle Joyeuse - not so difficult, as nastily awkward with a whole section with 5-3 crossrhythms, lots of hand passing and swapping notes.
Some of his Etudes are managable, ones which you should look at are "Pour les octave" and "Pour le arpeggio" (numbers 10 and 11).
Mouvement from Images book 1 is good also.
You might want to look at the preludes, not so many difficult ones, try "Ondine" and "Voiles", also "Minstels" is quite nice. They're all about grade 8 (though to be honest all are easier than the ballade).
Ravel isn't as approachable, but look at his Sonatine and Pavane.