Phylacteric Vault
Well, I don't really have a floorplan to the Vault, if that's what you're looking for. Instead, what I've basically done is create a bunch of locations within the Vault that my players have visited or heard about. The rooms have never really been layed out so that their location in regards to one another is known. Instead, I've always described it as, "You've left your quarters, traveling down familiar halls, until you've reached the soft din of the dining hall."
As far as specific and unique areas within the Vault, there are several that I've cooked up. For instance, there's the Planar Orrery, which is a vast, working replica of the planes that serves as a means of instant teleporation from the Vault to any point on Scarn (it's a one-way ticket, though). The Orrery was something I kind of built up during my campaign, only allowing it to become available after the characters reached some of the higher levels and needed the instant means of transportation. The Orrery was slowly built to completion while they toiled through the lower levels.
Another such room within the Vault is Nulan's Dojo. It is here where the fighter-mage of the group spends his time training. Hanging on the walls are the various blades of Vode Nulan that the Vault has collected. Thanks to the efforts of the characters, the blade Parting's Adherin now adorns the wall with the rest of the collection.
In addition to those two rooms, there are plenty of others, some mundane, others fantastic. There are your standard libraries, as well as the party's personal quarters. There's also the Curators' zoo, where all manner of dimensional beings are kept in captivity (the characters have never been allowed down here yet). In early sessions, one of the characters spent a lot of time with the oneiromancers in their dream chambers.
Basically, I think my subconcious inspiration for the Phylacteric Vault has to be Hogwart's School for Magic, from the Harry Potter series. Basically, you've got this magical place where you can run into anything. Just when you think you've got the place figured out, you discover a corridor leading to a part of the Vault that you never knew existed. It's the ultimate MacGuffin; an infinite number of available plot hooks.
So that's basically how I run my Vault. I sat down and came up with the rooms characters are most likely going to be interested in (living quarters, common rooms, dining halls, libraries, etc) and then came up with some plot specific rooms and just threw them all together and explained their location as being "somewhere in the labyrinth of the Vault."
Hope that gives you a few ideas.
Gaius
