This is one of the few Newbery winners that I read and loved as a child, though I never could remember the title correctly - I always mixed Konigsburg up with Frankweiler, and just last week I wrote "Frankenweiler".
Mostly, I remembered the kids living in the museum, sleeping in the antique bed, hiding in the bathrooms, and fishing money from the fountains for their meals. Somehow I thought that they made soup from ketchup from the free packets at fast food restaurants - but that scene wasn't in The Mixed-up Files, and a couple of files in my own brain must have been scrambled over the years. I do remember thinking about this book when my family went to the Art Institute and the Field Museum in Chicago when I was little. Chicago was also one of the places that I saw fountains with coins (there weren't any such fabulous things in my small town!), and I dreamed about swimming in the fountains around the sculptures, scooping up all that cash.
On my re-read, I appreciated the complicated characters that Konigsburg created (and illustrated! I didn't realize she did the wonderful drawings, too): Claudia, with her love of comfort - especially baths - and her careful planning, secrets, and her need for the occasional argument and something different; Jamie, the impulsive yet thrifty third-grade cardshark; and Mrs. Basil E. Frankweiler, the domineering, wealthy, eccentric narrator.
Claudia reminds me more than a little of my mother:
"She didn't like discomfort; even picnics were untidy and inconvenient: all those insects and the sun melting the icing on the cupcakes. Therefore, she decided that her leaving home would not be just running from somewhere but would be running to somewhere. To a large place, a comfortable place, an indoor place, and preferably a beautiful place. And that's why she decided upon the Metropolitan Museum of Art in New York City." (p. 5)My favorite quote, though (apart from the one Alicia already described about happiness here) was Mrs. Frankweiler's statement about knowledge:
"I think you should learn, of course, and some days you must learn a great deal. But you should also have days when you allow what is already in you to swell up inside of you until it touches everything. And you can feel it inside you. If you never take time out to let that happen, then you just accumulate facts, and they begin to rattle around inside of you. You can make noise with them, but never really feel anything with them. It's hollow." (p. 153)The whole bit about Mrs. Frankweiler and the experience of motherhood is something that went right over my head when I read it as a child, but that I appreciated today. Also, when I re-read The Mixed-up Files, I suddenly remembered my childhood satisfaction with the surprise ending involving Saxonberg. I still liked it, and indeed I still loved the whole story. Unlike the commenter who said that "as a kid, the promise of excitement was there in a museum" but that it wasn't the same as an adult, I still get excited at museums, even after working in one for years. Those drawers of artifacts and all of the files with their type-written letters and the carbon-copy replies still hold secrets and exciting stories.