Caliburn is the perfect warhorse, carrying Seona into battle, eyes in clear blue, gleaming coat in purest white, and barding of blue and silver. She's currently stationed in the Wetlands, though she may be moving on to the Arathi Highlands here quite soon. She's also considering purchasing a second mount for more casual riding while in the city or while traveling long distances. If she does, she'll be visiting the Amberstill Ranch in Kahz Modan, near where she was born. Being stationed in the Wetlands has acclimated her to living with dwarves again, as she has spent so much time amongst humans. No decision is made lightly, though, as she's going to need a great many upgrades to her armor when she reaches her next milestone, which costs gold, and a single mount is, in all practicality, enough for her immediate needs. Still, having a second mount would be nice so as not to tire Caliburn needlessly, and the hearty rams of her people would be excellent for her secondary purposes.
Less RP-ish: If there would be a low-level riding horse in white, like the NPC horse in Menethil Keep, I'd be rushing to get exalted with Stormwind now to buy one (Caliburn without armor would be nice). There isn't one, though, and I'm not going to go nuts attempting to get exalted with the humans for no reason. I do expect to get exalted with the humans first, and Ironforge second at the rate I'm going, but I don't know when I'll ever buy another horse, seeing as there isn't much point, even from an RP perspective. Makes me wish a visually simpler version of swift mounts were available for all the factions, not just humans.
When Seona hits 60, I firmly expect to do the questline for the mount, rather than just buy it. For one, you don't have to buy the training, which is quite expensive, and secondly, the quest is fun, slightly challenging, and lore-riffic. The experience you earn throughout the chain isn't bad, either, I've heard. Regardless, it'll be far better than just buying it, especially with my DK eventually getting to at least level 60 or so. I plan to get Ziir that high at least, at some point, to farm for stuff, just like Yrovi farmed for Mål.