I'm not running out of lots for sims to move in, if need be, but I always love seeing new worlds and new themes for the worlds. I tend to gallery-hunt for a certain theme and make sure that each neighborhood has its own distinct personality and theme. I'm also ridiculously fond of making sure they look good in the map view, too. Then I encounter super silly problems like 'these sims need homes, but none of the houses I have in my game fits them', but that's my fault, not the game's. o:)
I also set my favourite townies living in houses, sometimes whole families that I have no intention to play, so running out of lots is never about someone doing a rotational play between all those lots, it's about building consistent worlds and liking the way they're set up. My save is still the one I started when the game was first released. (I play aging off, obviously.) It's grown with the years, bit by bit, and I love it.
Expansion packs always bring a guaranteed world, but we just got one, so that's a long wait. Some game packs bring a smaller world, too, and although I think the next one will be a vacation world, I'm absolutely excited about that. Finally! Regardless, unless they bring out another Newcrest, I think the next livable world will be possibly maybe in another game pack later this year. Maybe.
Guess we all will learn to be better with condensing functions and revamping neighborhoods for a while longer!