Everything in the "In My..." series ("In My Pond", "In My Den", etc.) by Sara Gillingham & Lorena Siminovich
Fun and interactive, yet short and sweet, each book features an animal finger puppet you can wiggle from the back, while turning the pages. Eachends with the baby animal in their home (be it nest, pond, den, etc.) with their family. What I found unique about this is that the two “parents” don’t have gender-specific features (like eyelashes, bow ties, etc) to show they are “mommy” and “daddy.” This allows me to read these to my son (who has 2 dads), pointing out at the end which bird, fish, bear, etc. represents Papa and which represents Daddy, without it being confusing to him. Other than the fact that we’re, you know, animals. Also fun for kids with opposite sex parents! :)
"Creature ABC" by Andrew Zuckerman
A gorgeously simple book of animal photography. The dramatic photos elicit the most dramatic animal noises from our 2 year old, and you can tell he gets a little excited/nervous every time we get close to the L page. He often kisses the photo of the roaring lion, just to make sure it doesn’t pounce. (There's also a related floor puzzle!)
"Daddy, Papa, and Me" by Lelea Newman & Carol Thompson
Best book yet I've found portraying a 2 dad family. Fun, sweet, and reflective of real families — in that the 2 dads are exhausted at the end of a long day playing with their toddler! "Mommy, Mama, and Me" also available.