What is best way to get and play Age of Mythology on Mac?

I would try PlayOnMac, it's an easy-to-use wrapper for a program called WINE which basically replicates all the Windows code a normal win32 application needs to run. They have a database on their website of games that work on it, you might try there.

I ended up being patient and did not make any purchases until recently when Age of Mythology: Extended Edition was released on Steam. It includes the Titans expansion and is likely to have more content added like what was done for Age of Empires II on Steam.

I do have to boot into Windows to play but it runs really well (graphics look awesome) through Steam.