Note that articles with or of wood, requires fumigation certificate. It is the shippers responsibility to inquire and file this document with customs (US). Also the declared value is the COMMERCIAL VALUE of the item, not what you think it will cost but how much is the going price for such an item should it be available in the market - your furnitures. RE: Art if they are personal art - declare as such but if the art is bought in Argentina, it might behoove you to check the requirements of the US in allowing it to enter the US. Customs have been know to be a stickler in the ARTS department since the proliferation of stolen art pieces and fakes out there.
Good luck. As long as you have nothing to hide there should be no problem. Be prepared to pay some amount of fees in duties, taxes and tariffs.