Unless you know the kids to be above average, I suspect Max's suggestions are going to be over their heads - although they might be worth a try.
I second the Seuss recommendation(s). Even now I love them. (OTOH, I also loved Mr. Rogers into my late teens.)
I think maybe the 12 yo might like the HP books, if he has not already read them. Also, there's a trilogy called The Tripods that is quite good. (I think it was BBC that made a television series of it.) Also, the Chronicles of Narnia is good - particularly the first few books.
For the 8 yo, I recommend maybe the Captain Underpants books. (I haven't read them, but both my kids loved them.) Also, I think they liked James and the Giant Peach (didn't read that one myself either).
If you've got a few minutes to browse, you might check out the Newbery and Caldecott award winners for the last few years.
k
