If longevity utopia is an L-year lifespan for some large L and longevity dystopia is a ten-year lifespan, here's a longevity weirdtopia. Divide everyone's L-year life into L/10 ten-year pieces separated by long intervals of "pause" or "hibernation", and make these pause intervals so long that the group of people "awake" at any point in time is only a small fraction of the world population, with different people constantly rotating in and out. (I'm assuming here that total "awake" person-years and not total civilization-years are the limiting resource. And obviously I'm skipping over a lot of things, like procreation. But there's a lot of room to vary the scheme in response to all the obvious objections.)
Some reasons why I find this idea interesting and not just weird: 1) it would help solve problems involving Dunbar's number, 2) it might turn world history into something less massively parallel and more like a story, 3) there's a "deep time" feel, 4) I wonder to what extent it assuages people's sense (justified or not) that death gives life meaning.
Utopia and Dystopia have something in common: they both confirm the moral sensibilities you started with. Whether the world is a libertarian utopia of the non-initiation of violence and everyone free to start their own business, or a hellish dystopia of government regulation and intrusion—you might like to find yourself in the first, and hate to find yourself in the second; but either way you nod and say, "Guess I was right all along."
So as an exercise in creativity, try writing them down side by side: Utopia, Dystopia, and Weirdtopia. The zig, the zag and the zog.
I'll start off with a worked example for public understanding of science:
Disclaimer 1: Not every sensibility we have is necessarily wrong. Originality is a goal of literature, not science; sometimes it's better to be right than to be new. But there are also such things as cached thoughts. At least in my own case, it turned out that trying to invent a world that went outside my pre-existing sensibilities, did me a world of good.
Disclaimer 2: This method is not universal: Not all interesting ideas fit this mold, and not all ideas that fit this mold are good ones. Still, it seems like an interesting technique.
If you're trying to write science fiction (where originality is a legitimate goal), then you can write down anything nonobvious for Weirdtopia, and you're done.
If you're trying to do Fun Theory, you have to come up with a Weirdtopia that's at least arguably-better than Utopia. This is harder but also directs you to more interesting regions of the answer space.
If you can make all your answers coherent with each other, you'll have quite a story setting on your hands. (Hope you know how to handle characterization, dialogue, description, conflict, and all that other stuff.)
Here's some partially completed challenges, where I wrote down a Utopia and a Dystopia (according to the moral sensibilities I started with before I did this exercise), but inventing a (better) Weirdtopia is left to the reader.
Economic...
Sexual...
Governmental...
Technological...
Cognitive...