Island Living (especially since the emphasis is on indigenous culture and not resorts)
hula
Ukulele instrument skill
Surfing
poi
Hidden underwater world unlocked with mermaid interaction
Get To Work
mini adventure in Sixam that unlocks it as a destination or livable world on completion
Vampires
Vampire Hunter career. Now, I know the game doesn’t allow one sim to kill another, but vampire hunters could be about identifying vampires (research is already in the game) making a cure (already in game) and convincing vampires to turn back or capturing them.
RoM and High School Years
Cross pack compatibility for a magic school