Dwellings

Dwellings can be built however you want, in any architectural style you want, with however many floors you want. There will be some requirements, but the number requirements will be kept to a minimum, with an emphasis on player creativity. If you are running low on creativity, I'll try to provide you with a list of possible rooms you can add.
Each building material, room, and room upgrades will be given a certain point value. Each stage will have different point requirements for the various houses.

To advance each Stage, you should build a certain number of rooms, the number increasing every stage. Rooms can be any size, and can be single or multi-story. Some of the "Rooms" described here may not be literally rooms, but may be sections that may be nice to look at or use. The rooms will follow the same general categories as can be found in the Community Buildings page.
Villager Dwellings will usually be smaller than Player Dwellings, and will also have a certain number of rooms required (starting low, slowly going up). They can feed off the same list of rooms as the Player Dwellings.
An apology in advance for the lackluster Ars Magica suggestions. I haven't spent much time with the mod yet, and will be expanding the Ars Magica list as I discover more of its secrets.

Decorative Items List:


The Following Lists are NOT Exhaustive. Mods may have additional decorative items that could be added to the list, or I could be forgetting something from Vanilla Minecraft.

Indoor Decorative Items:

Outdoor Decorative Items:

Room Suggestion List:

Agricultural:

Residential (Bedrooms, etc):

Fortifications

Technological:

Magical:

Transportation (Minecart, path/road, and/or water-based):

General:

Work Room--

[Mod] Tinkering Room (Tinker's Construct)

Ore/Redstone Block Warehouse Room(s) (Blocks or Ore placed in groups for a visual representation of how much of each you have)

Item Storage Room

Additional Storage Room

Entryway

library

Infirmary

Bathroom

Armor/Weapon Display Room

Personal Mine Entrance (s)

Entrance to underground tunnel network

[Mod] Steve's Carts 2 Cart Assembler (Tier/Tech 1 Only) using the following Modules/Upgrades:

Stage 1: Dirt Hovel

Stage 2: Wood Settlement

Wooden Player House (Normal):

Must be sealed by a (Wooden) Door(s)
Must be bright enough so mobs will not spawn (at any time of day)

Must have work room:

Optional Rooms:

Wooden Player Dormitory (Fast Track)

Wooden Player House (Hardcore):

Players are NOT allowed, under any circumstances, to live together
Must be sealed by (Wooden) Door(s)
Door(s) must open by Wooden Button
Must be too bright for hostile mobs to spawn inside

Refugee Shack

Refugee Housing (Hardcore):

Stage 3: Stone Hamlet

Stone Player House (Normal) Additional Requirements:

Stone Dormitory Additions (Fast Track):

Stone Player house (Hardcore):

New House Must be built. Old House becomes Community Center

Hardcore Housing

Hamlet House (Elders)

Required Rooms:

Hamlet Hut