There might very well be different makes and models of skycoach in Sharn (all the more reason not to treat them like NYC yellow cabs). Nevertheless, my players have got the one from the Sharn street map, because that's what I used for the skycoach in the "Song of the Sky" adventure. It's closer in size and shape to the WizKids-produced skycoach "mini" (which has a deck that's 30 ft x 10 ft):
I note it has no discernable means of being piloted. I guess if a medallion is the way to control it, then you can mentally control it. (My players like the idea of a medallion, but they were hoping it wouldn't require attunement since they're all out of attunement slots. They might just have to hire a pilot.)
Thanks for the suggestions. However, I don't think those are really in keeping with bastion special facility benefits - at least not the lower level ones.
The bastion special facilities come in several tiers (level 5, level 9, level 13, and level 17).
An example level 5 special facility is the Arcane Study. It's Roomy, comes with 1 hireling, and lets you use the Craft bastion order. If you spend a long rest in the study, you get a charm that lets you cast Identify for free once in the next week. You can also order your hireling to make you an arcane focus for free over 7 days. You can also have your hireling make you a blank book. This also requires a week and costs 10 gp. If you're at least level 9, you can use your Arcane Study to craft a Common or Uncommon magic item from the Arcana table.
An example level 9 special facility is the Stable. It's Roomy and comes with 1 hireling and 1 free Riding Horse or Camel (or 2 free Ponies or Mules). You get advantage on all Animal Handling checks to control a mount after it has spent 14 days in the stable. You can order the hireling to buy or sell animals over the course of a week. You earn a profit when you sell an animal depending on what tier level you are at.
An example level 13 special facility is the Meditation Chamber. It's Cramped and comes with 1 hireling. You can use the Meditation to Empower your bastion's hirelings with Inner Peace so that the next time you roll for a bastion event, you can roll twice and take either result. You can also spend a week meditating in the chamber to gain advantage on 2 randomly determined saving throws for the next week.
An example level 17 special facility is the War Room. It's a Vast facility and comes with 2+ hirelings that use the Warrior Veteran stat block. You can use the War Room to recruit more of these hirelings (to a max of 10). You can get one of your hirelings to assemble a small army.
I suspect that will be rules around using an airship as a bastion rather than a rule for an airship docking station attached to your ground-based bastion. I note that there are also going to be 3 vehicles statted out in the book; I doubt the skycoach will be one, though. The airship, elemental galleon, and lightning rail are the most likely candidates.