I suggest experience given from all sources (Excluding pirates) Is raised. I rather dislike getting 244k exp for a pvp fight in phantoms at 163m power with double EXP. That's not even 100k per AP when my heroes take over 2 billion at only level 64. Building/techs giving more than the tiny bit they do for builders would be great too. =P
Perhaps pillars could also give experience to your heroes, Equivalent to personal damage you hit the pillar for. It's helpful though not massive.