None of these options fit the way I will play. For one, I won't be "fooling around". I'll be doing a casual balance of questing, leveling professions, exploring, trading on AH, dueling, world PvP, etc. The levels won't come particularly fast, but I'll be enjoying myself and making steady progress at the same time.
Just guessing, but I get the impression that the OP thinks anything that doesn't reward XP quickly is "fooling around".