Someone mentioned this 10 billion dollar project to create a "floating city" for the indulgent rich, and all I could think of was how it would make a perfect scenario for a Traveller heist adventure.
Bear in mind that the exact situation won't arise - the idea of the 'Freedom Ship' or whatever stupid name it's going on now is a ship that can permanently sit outside tax-controlled national waters. Since the Imperium claims interstellar space as its own territory, no parallel legal loophole.
That said, boarding some sort of Megaliner has to be a cool mission, and therefore must be done!
First thoughts:
This sort of ship isn't going to trek round space very often. Rich Nobles doing a 'grand tour' take their own yacht or (if they have any sense) a Huscarl cruiser. Several of them on a single ship is unusual, and - given the sheer movement of money, and social influence - the sort of thing that is going to be known for systems around.
A big passenger liner passing through the reach with diplomats and merchant princes aboard I can see, but that is essentially a variation on the Treasure Ship mission - and it will be guarded like nobodies business.
If you want lots of rich people on a liner, how about this? The liner is indeed luxurious but will cater to the middle nobility and rich commoners - it's literally going to run month-long honymoon cruises and the like towards the imperial borders. This trip, however, is the launching party, and - just this once - it's packed to the rafters with real nobility, as the launching of the ship is the social event of the season.
Alternatively, don't have it be a liner, but a space station - an orbital garden residency that assorted rich idiots have set up in orbit of a gas giant (as far as possible from the plebs on the mainworld). There's a non-trivial security detachment (even idiots aren't
that stupid or they wouldn't be rich anymore), highport docking facility, and fuelling station concealed in the underside of the station, but the stations main feature is a set of armour-crystal domes covering beautiful gardens, looking up ( I guess technically 'down') at the gas giant and its multiple ring systems and the aurora flashing along its upper atmosphere, one of the most famous sights in the system and one of the most beautiful in known space.
As noted, it will take a lot of planning. There is significant security to overcome, you'll need to figure out how to buy yourself time before the system navy reacts, how to dispose of the loot, and even what loot to grab (yes, the station is dripping with artwork and rich people, but can you identify which of the First Imperium sculptures are the genuine ones and which are replicas?)