I was accidentally subscribed to audible for the past year. What should I spend my 8 credits on?

I originally subbed to refresh my memory of Dune at work before part 2 of the movie came out, and incidentally forgot to unsubscribe.

I've gone ahead and spent 3 credits on Dune Messiah, God Emperor of Dune, and Children of Dune. And so I'm left with 8 credits to spend.

Are there any must-reads or general recommendations for me? I don't really dislike any genre in particular; Romance, Fantasy, Mystery, it's all on the table.