Personally, I think the first thing we should hear in Halo 4 is the Halo theme. Bust out of your cryopod while the Dawn is blowing up around you, and slaughtering Covenant to a hyped-up version of the Halo theme would be the best wake-up call the Chief could have.
I’d also like to hear The Last Spartan, Never Forget, and Leonidas return in some form as well as the classics like Walk in the Woods and some re-imagining of Under Cover of Night.