So I don't embed fonts in my epubs, because I feel like most readers ignore them anyways.
Instead I try and keep it simple, and get it down to either serif or sans-serif, with maybe one preferred font.
Something like this:
font-family: "Times New Roman", serif;
font-family: "Arial", sans-serif;
But what I've noticed is that not even these really come through. On devices like the iPad or Nook, it just completely ignores all my preferences on which font to use.
I have chapters where everything is in serif, except captions and the subtitle, but on my devices it just spits them all out as serif. On the Nook I can get it to work if I turn on the publisher's settings, but shouldn't these readers be using the fonts I recommend anyways?