We started reading the third Harry Potter book last week (the day after finishing the second book). One morning while my daughter ate breakfast we commenced chapter three, in which Harry rides The Knight Bus. Mid-way through, my husband spoke up with a question about the day's schedule. My daughter looked up, startled. She said: "Oh. I thought I was IN Harry Potter. I forgot that I have school today." And I thought: "YES!". What I said was: "Yes, that happens sometimes, when you are lost in a really good book." Needless to say, this was a good start to the day for me. It makes me happy that she can have, and express, that experience known to book-lovers everywhere.
One other note: As we watched the movie of the second book, my daughter remarked more than once, especially near the end, that things were not as she had pictured them. She had expected Tom Riddle to look more like Snape, but with longer hair, for example. I told her: "That's why we read the book first, so that you have a chance to imagine it your way."
As we move on to book 3, we leave the illustrated editions behind. And although I found the illustrations helpful in holding her interest at the start of the first book, I came over time to find them more of a distraction. I'm happy now to be moving on to the traditional editions, and I think my daughter is, too.
Wishing you all, and especially your children, that experience of getting lost in a book.