Many thanks to the blog commenter who suggested I read Ender's Shadow...it was fantastic. It takes place at the same time as Ender's Game, but through the eyes of another character: Bean.
The story covers a lot of themes including inequality, politics, and morality, but more importantly it's just a good story. I particularly enjoyed the beginning, which depicted a dystopian situation resulting from a society that has no safety net.
You don't have to have read Ender's Game to understand this book, but I still recommend starting there if you're new to the series.