how do you furnish a mansion?

Just think of the board game Clue. :D You've got your Conservatory (indoor garden room with fountains, etc), your Library (must have tons of bookshelves, cozy chairs and fireplace), your Ballroom (jazz it up with a DJ Booth if you have one, or go formal with a piano, etc), Billiard Room (a Game Room until we actually get pool tables), the Hall (large misc room with portraits, settees, hall closets, etc), your Study (sort of a glorified office). The Lounge is basically a Living Room, that can be huge, with little conversational nooks all about) and the formal Dining Room can contain a massive table. Your Kitchen could have a separate Pantry, with a couple fridges, and a Breakfast Nook. There should be plenty of Guest Rooms for folks who want to come and mooch off you visit, perhaps even a guest house with all the trappings. The Master Suite could have His and Hers Dressing and Bathrooms, and all bedrooms need a walk in closet of some sort. Every mansion must have a Pool House in my book, with the accompanying Spa/Fitness Room depending on the packs you have. The back garden must contain a gazebo; I have a display of beautiful insects in one of mine. For your scientific types, you can have a Laboratory--those take up tons of room. Most evil tycoon types have a whole separate wing for the kiddly winks, and their nannies, nurses, and accompanying staff. Oh, don't forget the Butler's quarters, and you may want to have a live in maid as well....I could go on....