After 20 years of working with young children, I can attest to the fact that they like almost anything. In the child care facility I work in, we play everything (I play a lot of celtic/traditional songs, rap, hip hop, hip hop religious (we're non-denominational, cross cultural, etc.) and drumming music is a hit....classical, you name it. However, to rock the babies, I hum or sing "Old Texas" or "One Johnnie Cuckoo" because it is repetitive, which is the key to getting them settled to sleep. The older children love anything that's silly such as:

Bear Hunt
Down by the Bay
Goldilocks
Boy and girl...canoe
Teddy Bear, Teddy Bear
Sleeping Bunnies
Singing in the Rain
Skinamarinkydinkydink
Working on the Railroad
New River Train

and on and on and on......especially if there is participation!