What were the main features of an Upper Class house in the 1800s?
The answer above is pretty comprehensive. Most of the bigger houses would also have had a library/study and possibly a games room for the man of the house, while the woman would have had a private parlour, as well as a larger withdrawing room for when the ladies left the gentlmen at the dining table for their port and cigars. This room, if big enough, could also be used to hold small private parties, while the really big houses owned by the aristocracy would have had their own ballroom. There would also have been a breakfast parlour, separate from the dining room, which would seat a lot less people – most women tended to eat breakfast in their rooms, while the men tended to gather for breakfast.