While I can't give you any specific designs for your project, I recommend looking at other examples of designs that have been used for similar projects. Start with Google images and look up things like, "CD Cover Design" (Is this for a CD Cover?) And, see if any particular style grabs your attention.
Also, think of your audience. Children's music is very different from Hard Rock, Oldies, Folk or even Speed Metal or Punk music. Each will have their own image that is related toward a specific audience. There is a good website that has a lot of information on album cover art: sleevage.com There you will find many examples of excellent album cover art from all genres.
Good luck with your project!