The general consensus, at least in the academic world, is that because Dublin Core doesn't define support for subtitles, you should shove everything into the title, separated by a space, a colon, and another space, e.g.
Code:
Alice's Adventures in Wonderland : A Thrilling Adventure of Psychoactive Substance Abuse
I definitely would not try to use EPUB3 functionality at this time. Give it a few years for it to gain more acceptance/support by reader vendors.