Modes are good too since the moods are very flexible in each tonality.

Ionian- happy
Dorian - Sad folky sound
(spanish) Phrygian - Exotic
Lydian (dominant)- triumphant, warlike
Mixolydian (b6)- Happy folkish [ the 'b6' version being more like a bluesy folk sound]
Aeolian (melodic minor)- sad, downish
Locrian (#6) - very dark

These are some of the ways I've heard these modes described or used. Looking at each you should see how each can bring in a certain sound to fit the context you have at the time. And in an epic you want to progress through a few.