My kids (age 2 and 3) love books, and I am constantly on the lookout... It feels like we've read all the popular titles already. My 3 year old can sit through chapter books (i.e., Stuart Little, Cricket in Times Square, etc.), but still enjoys picture books (i.e., Owl Babies, Dr. Seuss, etc.). Please offer your opinions: what are the best titles out there for kids (6 years old and younger-ISH)---chapter books as well as younger picture books?
P.S. Not to limit the response, but my boy especially loves trains and owls, and my girl princesses and baby animals. We are already familiar with Thomas the Train books.