In my bid to unintentionally dominate every discussion topic I just came up with a rather interesting idea that might help make each spacecraft feel like home:
You hire crewmembers to fill passenger slots. Each crew member can have specialties that can aid you. One might be good at using turrets, which will give you a slight increase on recharge time, damage, whatever. Another might be a first aid expert which will increase the time that mortal wounds take before they kill you, allowing you to get to an autodoc (though they can't do this indefinitely). Others increase sensor range slightly, or give you bonus to negotiation if you accidentally hit a friendly, or once in a while give you inside trading tips as if there were extra news bulletins, or help repairs go more quickly, or recharge shields slightly faster, or increase salvage yields, or chance that asteroids will yield materials, or slowly alter faction standings, or reduce fines... that sort of thing. One character might have multiple skills to increase their usefulness.
The tradeoff is paying them like you do mercs, though not as much, and losing a passenger slot that you could have used for missions. If you can't pay or won't, they'll get dropped off at the next planet you land on, and if you trade ships they'll be standing next to your ship in the docking area, where you decide who is going to stay by talking to them and basically hiring them again.
I'd say that they either hang around at the bar, or maybe hotels will have a little area on each planet where one will hang out.