One of my favorite pieces in the French book is Andante et Scherzo by Louis Ganne, though it is rather beastly to put together with piano accompaniment. (At least, I thought so when I played it in high school.)
The Poulenc sonata is beautiful, and lots of fun as well. It really makes you clean up your third octave double tonguing, if I remember correctly.
Have you played the Hindemith sonata? Personally, it's not my favorite things to listen to, but I loved playing it. It's also an important piece to have played if you plan on pursuing music in college.
For my juries this semester, I'm playing the Ewazen flute concerto. It was written in the 1980s, but rest assured, it is absolutely tonal. It's rhythmically challenging, but it's gorgeous when it all comes together with accompaniment.
There's heaps of amazing music out there.