nice, Dvorak and Sibelius are favs but i'd probably only take Dvorak. it can't all be symphony.
i'd add in john williams (the classical guitarist, not the movie theme composer)
OK, orchestral - including violin, cello, and piano concertos.
gotta have rostropovich playing Dvorak.
I'll also add Debussy
I imagine being on an island will be boring, relaxing at night listening to this stuff would be more enjoyable to Metallica or Iron Maiden. :-))