For the world, I asked for a mythology based world, mostly 'cause I'm more interested in the clothes and hair than the world itself. For the theme, I asked for a pilot/flying set - for radio controlled helicopters/planes, or a treehouse that is a "tree-jet", things of that nature. And for the premium content, I came up with a "little black book" or something that, if you have a family move neighborhoods, they retain the relationships they had in the old neighborhood, and can invite them over, like tourists from WA.