I GM'd a group through 1st & 2nd edition up to around 11th-12th Circle. The core of it was the epic adventure path: Infected -> Shattered Pattern -> Blades -> Prelude to War -> Barsaive at War... with various home-made stuff interspersed through it all.
It did start to break down at 9+ Circle, but we had also shifted to 2nd Ed around 7-8th Circle and there were problems in the higher circle stuff in 2nd (IMO). Circle 8+ stuff can really get interesting, but I do agree that it can seem impractical (which is a cry for more advice for that kind of play).
Some of the things my players did at higher Circles (8+) and had an Airship to get around and were dealing with the Dragon level politics leading up to Prelude to War. (Spoilers minimized, mostly focusing on the player initiated plot arcs.)
Elf Warrior (who started a romantic relationship with Maloniel from Infected, who I had made an elf maiden):
- Wrestled a leviathan to submission and won a set of Named Legendary blades (the shorter of which acted like Scorpion's chain-whip, which saved him from falling off the airship many a time). Various adventures (some done as "blue-book" solo play) spent researching the Legend of the blades.
- Cleared a "hex" in the Throalic Mountains, and was awarded it as his land after various favors from the crown (Shattered Pattern stuff). Became a passion-honest "landed Lord" with his Lady.
- Hired as many elven architects from Bartertown and various outlying communities as he could to cover "his valley" with elven "blends so well with nature you can almost overlook them" towers and small fortifications on the ridges, passes, and near important places like fresh water.
- Trained up a Warrior Order, using as much pre-scourge elf martial arts as he was able to recover from various kaers (& politics at the edge of the Blood Wood). Non-adepts welcome!
- Repulsed major raids and scorcher incursions while this was being setup. Various tribal politics to get his people a safe place and building ties to the nearby dwarf/human/orc towns. Started inviting all other elves who didn't want to put up with Alachia's bullshit to come and live an "authentic" elf life. Dealt with the bad blood that stirred up and ousted multiple of Alachia's "Songbirds" and a couple of Assassins from his community (it helps when your Lady is a High Circle Thief, low Circle Illusionist).
- Discovered and suffered from Cave Crabs raiding all their shit from the highlands above the valley. Mapped out the cave-system with the help of another player and bunch of his Order (mid circle adepts and lots of non-adpets). Discovered he had a Cave Crab breeding ground in a huge underground lake above his valley. Leveraged this into proving Cave Crab meat to all the dragons the party was semi-friendly with, earning HUGE gold-stars from all of them. These favors were called upon during Barsaive at War.
- Manages to get the attention of Thystonious (personal appearance in public, think Eris at the end of Sinbad and the Seven Seas) after some major skirmish action during the lead-up to Prelude to War, and then he convinces the Air Sailor Captain to fly over the enemy lines performing a war-dance on the ship's railing (gods, THE EXPLODING DICE). Oh, as this arc involved some of Blades, this was also a fight over the Shrine housing the remains of the original ork warriors that owned the Blades with both Therans and the forces of Cara Fahd wanting to snatch the players and everything they had pulled out of the tomb.
Human Airsailor, Captain of their Airship:
- Improved relations with the more open Trollmoots. Was taught shipbuilding, started a small shipyard in Throal & one in the elf's valley. Hired a bunch of specialists for the shipyard. Built her own ship & trained up/hired the best crew she could find from various parts of Barsaive (the crew was super abstracted as the 1st/2nd Ed Ship rules really leaned that way).
- Raised a Griffin familiar from a cub & invested enough magic that it wouldn't get splatted by high level play. Took up a few Circle in Cavalryman (woman?) to further advance her as a Named animal companion.
- Crafted her own Legendary Treasure, a spear made of orichalcum laced ironwood tipped by the worked tusk of a "Crystal Boar". Bound a Named spirit to it by acquiring Pattern Items, some Thread Magic and some on-the-fly Test-of-Wills. After forcibly binding it, convincing it that she had it's best interest in mind by protecting and cleansing the holy high places in the Twighlight and Throal Mountains.
- CRAZY shit during the 2nd Battle of Sky-Point. Inverting her ship to drop the marines (who aren't strapped in like the crew) onto enemy vessels. Direct attacks on ships wile her ship was dealing with other targets, etc. I tried to get creative, but that's where the existing mechanics weren't helping me out.
I hope this is inspirational. Let's talk about what kind of advice we all would like to see for such "High Circle Campaign Play".
Edit:: Oh, one more thing that jumped out at me from my memories. At this point, the preferred method of the Assassins (from the Castle of Assassins in the Mist Swamps) to first engage with the party was to throw an orichalcum orb with a bound and very angry earth or fire spirit at them which was set to release upon contact with earth or wood. Preferably from like, the next rooftop while the party takes ranged and spell attacks, and then sniping at them from cover while they deal with it. I sincerely apologize to any group that now has to suffer from this tactic.