These little hardbacks, a collaboration between Puffin Books and Rifle Paper Co., are some of the most beautiful editions I own. I think that Children's Classics should appeal to adults and kids alike, which makes this collection pretty much perfect, in my opinion.
Alice's Adventures in Wonderland is not technically part of the collection, but the design goes so well with the rest of the books that I'm including it here. The other editions can be purchased separately or as a box set.
Box set (does not include Alice): 9780147518743