Listmania!
Viva Aida Marcuse!
By an Amazon.com customer
Huevos verdes con jamónHuevos verdes con jamón by Dr. Seuss
Buy new: $9.95 / Used from: $3.94
The best Dr. Seuss translation.   If you want to introduce your child to a little Spanish this is a great choice.
More Spaghetti, I Say: Quiero Mas Fideos!More Spaghetti, I Say: Quiero Mas Fideos! by Rita Golden Gelman
Buy new: $3.99 / Used from: $0.01
Cute, simple story for very young children, equally good in Spanish or English.   If your child liked Huevos Verdes con Jamon, you might want to try this next.
El LoraxEl Lorax by Dr. Seuss
Buy new: $10.17 / Used from: $6.12
Beautifully translated, but my son's not ready for it in Spanish , though he loves the English version.  All the made-up Seussian words were apparently too much.   I'll try again when he's older.
Listening Walk, The (Spanish edition): Los sonidos a mi alrededorListening Walk, The (Spanish edition): Los sonidos a mi alrededor by Paul Showers
Buy used from: $8.48
An unjustly obscure classic (somewhat in the mode of Dr. Seuss' "Mr Brown Can Moo"), wonderfully rendered into Spanish.
Tu mama es una llama? (Spanish Edition)Tu mama es una llama? (Spanish Edition) by Deborah Guarino
Buy new: $12.48 / Used from: $32.07
Aida Marcuse has translated hundreds of children's books, often uncredited.
La oruga muy hambrienta: Board Book (Spanish Edition)La oruga muy hambrienta: Board Book (Spanish Edition) by Eric Carle
Buy new: $7.91 / Used from: $5.58
Another brilliant, although uncredited, Marcuse translation.  Not only are her translations excellent, but she consistently chooses wonderful books to translate.
Oh, cuan lejos llegaras! / Oh, the Places You'll Go! (Spanish Edition)Oh, cuan lejos llegaras! / Oh, the Places You'll Go! (Spanish Edition) by Dr. Seuss
Buy new: $28.10 / Used from: $29.56
One of Chris's favorites right now, he likes for me to read the English and Spanish versions back to back.  He didn't really like it before, though; this is probably too abstract for most preschoolers
El conejito andarínEl conejito andarín by Margaret Wise Brown
Buy used from: $0.01
A classic of course, and perfectly translated.  Too easy a translation for such a great translator, though.
El Gran Granero RojoEl Gran Granero Rojo by Margaret Wise Brown
Buy new: $7.99 / Used from: $3.10
Charming and very simple--my son is now past this in English, but still enjoys it in Spanish.  If your child's progressed further in one language, he may want different levels of books.