Tolkien, Rowling My 12 yo and 9 yo read all the Harry Potter books 1 1/2 years ago and loved them. They have just read the Tolkien books and loved them. What other books can they read that have complex plots and characterization but are appropriate for their ages?
Oh no! They've read Tolkien? After that, there's nothing that compares.
I could recommend other good stuff, but then it would be apples and oranges. I can think of nothing that matches Tolkien's combination of (1) quality, complexity & sophistication, on the one hand; and (2) compulsive entertainment value, on the other hand; and (3) age appropriateness.
Commercially-successful Tolkien imitators include Terry Brooks and Robert Jordan. I found Terry Brooks unreadable, and never ventured Robert Jordan.
I might recommend Lewis' Narnia series (which is good, though not as good as Tolkien); but then you might suspect me of trying to convert your kids to Christianity.
More in the line of horror are two of HP Lovecraft's longer works THE CASE OF CHARLES DEXTER WARD, and AT THE MOUNTAINS OF MADNESS, both of which I liked, though characterization is not a strong point. Both works manage to avoid the virulent racism that crops up in some of HPL's other work.
More specifically kid-oriented horror is John Bellairs THE HOUSE WITH A CLOCK IN ITS WALLS. Probably his best novel. He wrote many many others, but I'm afraid it's probably all downhill from there.
I remember enjoying H. Rider Haggard's KING SOLOMON'S MINES at that age. But I remember very little about it now. I suppose it probably contains 19th century racial attitudes.
You might try to introduce them to the real ancient classics (The Iliad, the Odyssey, Beowulf, etc.) But this would not have worked with me at that age.
Appropriate for those ages, definitely not the A Song of Ice and Fire series. Maybe some of the Timohty Zan Star Wars books if they enjoy the movies. Ender's Game is sci-fi but is definitely a good read and appropriate for kids. It is about children as well.
Since my original post, my kids have been reading all of Tolkien's other works. They have also read Beowulf and The Odyssey. I am still looking for other works of fantasy or science fiction for them. They are still ages 9 and 12. The need complex, quality fiction with great characters that is appropriate for their ages.
There are some very enjoyable science fiction series such as The Well World series by Jack Chalker. An ancient species The Markovians decides that they've reached an evolutionary dead end and voluntarily transform themselves into other species to see if they'd missed something. In the process they create a new and much larger universe, the one we live in. Much of the story takes place on The Well World which is where the Markovians began their speciation.
Another that I enjoyed from my youth is the Gaea Trilogy (Titan, Wizard, Demon) by John Varley. It is centered around a living, sentient space station discovered orbiting Saturn but has a very engaging element of fantasy in that the space station is insane and creates creatures within itself for its own amusement. Then people find it... There might be a little too much sex in this series and many of the themes are fairly adult, but it really is a good read. Maybe when they're a little older.
The Ender series by Orson Scott Card may be more appropriate as the main character starts the series as a child. A very special child trained to save the human race from alien invasion. It sounds simple but its not, complex moral issues are brought into play and the series continues following Ender Wiggin as he grows into adult hood and becomes an ambassador of sorts to other alien sentient races. Great characterizations make this a pretty special series. There is some violence but its absolutely appropriate to the story and no more violent that Beowulf or Harry Potter certainly. I think they're making a movie of the first book Enders' Game.
Forgot one, The Earthsea Trilogy by Ursula K. LeGuin. Fantastic story concerning Wizards on a planet that is mostly ocean dotted with archipelagoes and some larger continents. Great books by a masterful writer. She has a different take on magic that makes the stories unique.