Again, once you have one where you like the look, you can change the theme font. Then save it as a custom theme.

Also, pay attention to the [Quick] Style Sets which make up the bulk of the Design tab. Those are the styles changed by themes and they can also be modified. This is because they all use theme fonts and theme colors.

Word 2007 and 2010 had themes that were discontinued with Word 2013. I would recommend downloading them all and checking them out.