I really want to see all my PCs (or at least several of them) sitting in a bar, hanging out. I figure this would make a nice option for the character-selection screen.
Basically, I want to see my characters sitting around in a bar, as if they're between missions. Perhaps they wander in & out. Maybe they occasionally speak to each other. (There are probably some greetings & farewells in the audio already recorded from the voice actors.) I'm not looking for complex or controllable interactions. I don't need access to their inventory or any information about them not readily available on the load screen.
I want to take screenshots with several of my PCs present at once. Perhaps some banners or emblems on the walls for the account-wide rankings, as an upgrade for the current load screen. The bottom character-select bar could be retained as is.
The game already contains several fully-rendered 3D locations where this could be set: Each of the six major cities has a bar or restaurant. Additional locations could be drawn from Tarir, Amnoon, the PVP lobby, and the various Lounges.
I think the 500-gem price for a mail carrier is appropriate for each location the characters can appear, or perhaps a little more: All of the locations, character models, and audio already exist. I also think many players would be interested in such an upgrade. We just need a little coding to link them together.