I think the herioc part of DDO would do well with more reason to play different quests each life. After running many lives and some Hard Cores many players tend to stick to a smaller subset of quests, the ones with the better xp.
I would like to suggest the following. Each month a specific "Favor" is the "Favor of the month". This means that all quests that give that particular favor give double regular xp in heroics during that month.