The double experience bonus includes all forms of XP except Guild experience.
Colette "Dexella" Murphy posted on the official forums:
Enjoy Double Experience this weekend in EverQuest II! Starting at 12:01 pm (noon) Pacific on Friday, February 22, 2013, and lasting until 11:59pm Pacific on Sunday, February 24, 2013, we’re offering Double Experience in EverQuest II! Take advantage of this limited time offer and watch those XP bars fill up!
When asked, Dexella told us that the double XP includes all forms of XP except Guild experience.