Do 9Tails, just be sure to remove all ninja except your main (with least damaging standard) to 1st hit and run off to anywhere else. That gets you around 35k exp but you get some sun scrolls and a magatama so it's not that bad a deal.

In level 70 jinch rescue I can't recall what the rewards are, but I'm pretty sure you shouldn't do it.

For whatever events that come up having you gain exp in some way you'll have to decide if how much exp you get is worth the rewards... Can't really tell you what to do or not with those.