So, continuing down the list of beastmen: Ogres, Giants, Trolls. The big guys.
I've always felt that elemental giants were kinda stupid. I mean, fire and frost are Norse, so there's a strong mythic resonance, but unless you're doing something very nordic where Frost Giants are a faction, I don't think they're super important. Let's cut them. Hill and Stone giants are boring because they're just big dudes. They don't have any real narrative purpose that couldn't be filled by an ogre or a bandit with hefty thighs.
Cloud Giants are really weird though. Weird enough that we can extrapolate something interesting from them. Who are they? Why are they in the sky? I can't think of a really cool biological reason why they'd be in the sky. I don't think they're like, seagull beastmen, or they just naturally need that vitamin C (clouds.) I think living in the sky has to be a choice. What does the sky have to reccomend it? Well, safety from natural predators, but if you're a giant with the know-how to build a flying castle, you probably don't have any predators. I guess we don't know that the castles fly. They could be on naturally flying islands.
I think cloud giants live in the sky because it's a preference. A flying castle is a great lair for a wizard. The sky is peaceful and isolated, and you can simultaneously travel to look for magical ingredients and stay at home! Plus, wizards love height. It's a fact; that's why they always build high towers. A flying tower is as high as it gets. Now, not all cloud giants are wizards per se, but they all lead wizard-shaped lives. There's probably a castle with a cloud giant swordsman who does research on different sword techniques and is searching for the perfect sword metal, and he's written book-length essays with titles like "On the Viability of the Capo Ferro Maneuever In Opposition to Thibault: A Close Examination of Agrippa and the Unseen Geometric Implications of the Thrust: A Rebuttal."
I imagine that the success of this lifestyle varies wildly. Some actually do wind up achieving tremendous progress and become masters of their art rivalled only by the world's greatest. Others probably just waste their lives writing bad books and speaking pretentiously about how enlightened their isolation makes them, like a whole race of Henry David Thoreaus.