My FC bought a large mansion in Grid. We decorated it with the 200 limit, using "big" pieces to fill in certain areas. It *still* looks pretty spacious and barren. We did not go partition or bookcase crazy. Please don't say 200 is enough. It is not. I don't think even 300 is enough.
A group of friends and I bought a medium house (in an alt FC).. The house is very detailed, but I can see it needing more than 150 if we're allowed to put anything in the incoming 2.2 airship/ship building area. Medium's furniture limit is the one I'm least worried about though.
I bought a 'personal' small house (yet another alt FC). With the floorspace being doubled + basement being put in + airship/ship crafting area, we'll definitely need more than 50 furniture....