What should I add to my running playlist?

All right, I know this question has been asked before, but I think since the answers change with time, it’s okay if I ask it again? (But, lovely mods, feel free to correct me.)

I am heading out on my first double-digit mile run today. (There, I said it, so I can’t back out!) I expect this will take me close to two hours, and my running playlist is just a little too short. Any suggestions of things to add? Right now I have a bizarro mix of that includes the poppiest of pop music (Madonna, Rihanna, Lady Gaga) to country (Brooks & Dunn) to standard white girl music (Guster, TV on the Radio). So I’m open to pretty much anything.