I don't know how hard it would be but I was thinking about a personalized destination for your characters. Kinda like yodas hovel when Skywalker went and trained with him .if you go there your other characters would be standing around and you can trade characters. Also maybe have an armor room and weaponry room or combined war room where you can have all your exotics on the wall. For display. Maybe customize the "homebase" with items or drops from around the solar system..ie vex head lamps or stuff like that. Let your imagination guide you. Finally if you are fire team leader you can bring them to your intergalactic pad to chill and plan stuff. Just sounded cool to me and could expand on vault space that way. Maybe you even have to run a mission with friends to capture this persoral pad. Whatever.
What do anyone else think?