For multiplayer fun, nothing beats Age of Empires III with both expansions, I find. Starcraft is balanced but I got really tired of it--the graphics, the jerklike people who I find play it, and the overall playstyle, which tends to be "rush and kill them" all the time. Age III's levelling home cities give you a reason to keep playing multiplayer aside from the matches themselves. Plus it's diverse and dynamic. I just wish they added European/African/Mideast maps to it, since they have the Americas and Asia represented.
For single player epic missions, I love LOTR: Battle for Middle Earth II, for single player stories and mission balance nothing, NOTHING beats Age of Empires II. Its historical campaigns are what got me interested in history. Or....if you're thinking strategy as in parties/use of powers, Baldur's Gate II or Dragon Age: Origins. Lots of tough fights in both, and key decisions to make when you pause the game.