Silly me, I never bought a full reading program past second grade. I figured once we past the "learning to read" stage, that we could pick up pretty much anything the kids or I felt like that week and start reading.
Our last book was The Twenty-One Balloons by William Pene DuBois. I have to wonder whether the fellow was being silly when he wrote the book or was trying to comment on some sort of Utopian form of government. The plotline goes like this: a mathematics teacher decides to escape from teaching children by embarking on a year-long balloon cruise. He winds up marooned shortly after on an island full of children the exact age he had been teaching at home.
Their parents have all named themselves the letters of the alphabet up through T. They each have one boy and one girl child and are part owners in a very productive diamond mine. If they were to leave the island permanently, the value of the diamonds they'd bring out would bring down the market. If they stay, the volcano may blow up at any time, rendering their diamonds more than useless.
I'd recommend the story for readers a little older than 7 and 8, the ages of Emperor and Elf. Much of the social commentary went over their heads, though they were able to enjoy most of the story.
Next up on our list is "James and the Giant Peach" by Roald Dahl.