Septim Mansion is one of the best house mods out there, IMO. I've been using it for years, though it took me awhile before I started making changes and alterations to better suit my tastes. I've gotten to the point where I'm happy with things as they are, and since Sietse gave permission to "distribute and modify this mod freely", I'd like to share it with the community at large. Note that this is built off v1.2, NOT 1.3 - I didn't care for all the extra NPCs and other changes he made, so I stuck with 1.2. The changes I've made are quite extensive, so if you're already using any other version of Septim Mansion, you should make a clean save - remove all your stuff from the mansion, deactivate the esp, save the game, then install my version.

--General--
* Removed all the freestanding candles (not the candelabras), except the ones on the shrine - they simply weren't necessary, and many of them were placed in really odd spots (on bookcases, near plants, etc.).
* Added a few dozen mannequin pedestals and some diplay cases in various locations.
* Grounded or adjusted various items.
* Fixed some errors in the scripts.
* Removed most of the skill books (there are still a few floating around).
* Moved the Septim Mansion book to The First Edition to ensure compatibility with mods like Better Imperial City, and removed the ownership.
* Cleaned the esp with TES4Edit.

--Armory--
* Added weapon racks and two cabinets for armor.
* Made the repair hammer chest non-respawning. It comes with 10 hammers, but you can use it for storage now.
* Added a custom AI package to Valdus so he doesn't follow you around, and a wander package so he doesn't stand in one place all day.
* Grounded a floating chair.

--Bedroom--
* Added more place settings (some were missing), and added food and silverware as necessary so all the place settings are complete.
* Added a winerack (container) near the dining table.
* Removed persistence from the dining table and several chairs.
* Disabled the dog.

--Display Room 1--
* Removed a few items from the shelves.

--Display Room 2--
* Moved some of the candlestands, and added more for better lighting.

--Entrance--
* Cleaned out the cupboard near the bedroom.
* Cleared off the bookcase so you could use it for displaying items.
* Fixed the misaligned passage leading to the bedroom/storage room.

--Library--
* Removed the books chest.
* Added two static book containers on the shelves for skill books and other books.
* Added three sets of drawers on the shelves for notes, maps, and other documents.
* Removed the more powerful spell scrolls.

--Storage Room--
I use this room for storing quest items, instead of items in general. To that end, I:
* Removed the table in the middle of the room.
* Added a weapon rack, Ayleid cask for keys, and moved the jewelry boxes to the desk.
* Named most of the containers (the armoire and chests in the back corner are unnamed, so you can use them for whatever).
* The chests and armoire in the second storage room remain unchanged, if you want more unnamed storage.

--Vault--
This is a new feature. I stumbled across a room buried deep in the caves one day; it originally had an Oblivion gate with an activator (presumably you could use it to go to random Oblivion planes, but it wasn't functional). I saw it as a perfect place to add what I really wanted - a vault. The only way to get here is via the teleporter; there is a secret rock door in the caves, but I never bothered to make it functional - it's too far to walk, and I like it being cut off. I ripped out the gate, replaced the activator with an Ayleid crystal, and added the following:
* Six named chests for coins (if you have a mod that adds Ayleid or Dwemer coins), metals (nuggets, bars, ores, etc.), gems, and jewelry.
* Several display cases for the really valuable stuff.

--Wizard Tower--
* Disabled the bear in the lower level.
* Replaced the Master-level apparati with Apprentice-level ones.
* Added a scroll rack (container).
* Added a pair of bookcases, along with a book stack (container) and two drawers.
* Raised one chair that was sunken into the rug.
* Added Ayleid casks for storing varla/welkynd/sigil stones and soul gems.
* Replaced the Poisons chest with one for ingredients.