The WHERE'S WALDO? books, by Martin Hanford, became a craze in the late 1980's. While I can't deny that this cartoon-style series is fun, see my recommendations below for some extra special choices...
EACH PEACH PEAR PLUM by Allan Ahlberg, illustrations by Janet Ahlberg (ages 4-8) Nursery rhyme characters sneak their way into gentle drawings - in the cupboard, on the stairs, in the forest...little ones will love this clever story! Also look for: THE JOLLY POSTMAN, where every other page is an envelope containing letters to fairytale characters. For example, there's a note for the Three Bears from Goldilocks, who not only apologizes for the trouble she's caused, but invites Baby Bear to her birthday party. Adorable!!
ANIMALIA by Graeme Base. (ages 4-8) This, the first of many original books by Base, is an elaborately illustrated alphabet book of paintings like no other you've ever seen! Packed with detail and layers and layers of objects matched to their corresponding letter on each two-page spread.
I SPY... (series) by Walter Wick, began with I SPY: A PICTURE BOOK OF RIDDLES, published in 1992. All the books have riddles by Jean Marzollo, in two-page spreads of objects hidden in photographs by Walter Wick.
CAN YOU SEE WHAT I SEE? (newer series, ages 4-8) written and photographed by Walter Wick. These books not only have riddles, but also puzzles and brain teasers matched to the pages jam-packed with photos of objects to be found.
CAN YOU SEE WHAT I SEE, SEYMOUR? (ages baby-preschool) Same as above, but for a younger crowd.
LOOK-ALIKES: THE MORE YOU LOOK, THE MORE YOU SEE! (series, ages 5 & up) by Joan Steiner. These amazing books are full of photographs and riddles, but unlike Walter Wick's series, Steiner photographs three dimensional scenes that are made of everyday objects - like matchboxes, pretzels, crayons, and slices of bread, that double as trucks, chairs, a sidewalk, etc. Delightfully deceiving!!!
LOOK-ALIKES JR. (series, ages 2 & up) "To Look-Alike Land! We're blasting full throttle on a spaceship that looks like a THERMOS BOTTLE!" You've got to see it to believe it.