I don't know how interested you would be in doing this. But I figured I would suggest it anyway. I notice in a decent amount of RPG's there is a fair amount of customization when it comes to properties.
For instance you can buy a house and then decorate it. In BYOND, this could be done by having a house selling NPC who sells you a property and gives you a key to it so only you can get in (Unless you have more keys made and give them to other people). Giving you the key to the inside of an empty house or whatever, and then you can buy items such as rugs, chairs, tables, chest, ETC, to fill your house with. The only issue is that once you reboot the server this will remove all that work that you have done.
I under stand that swap maps can be used to save the interior of buildings in a situation such as this, so that when a player comes back to the building it is as they left it. Which would be cool and interesting to see in a RPG framework as it allows for character customization of there players.
I think this would also be kind of of interesting if mixed with Deadron's Calender library (Or a even something that you make yourself that is similar) that can add customizable time to the game. Such as regular months and days, or some kind of wacky special months and days specifically for the game. This could allow for seasons. Which I think, swap maps might also be useful for, because it could allow you to have a winter map with snow, or a fall map with fall like pumpkins or leaves on the ground, or a summer/spring map with more flowers or something, that adds some type of depth and character to the game. as the maps are not always the same and now there is a time system in place which could allow for other things as well.
I suggest this because I have always been curious about how to implement swap maps into a game, but have never really seen a great example of how it could be used and used correctly. So I think this would make your frame work more interesting as well as give a great example on using swap maps and even Deadron's Calenders to make unique qualities for the game (so they aren't all just cookie cutter imprints of one another)