In the long-term I would prefer .US for real estate domains with a connection to the United States (i.e. nevadarealestate.us). In fact, I would only use .US if there was a connection to the United States.
In contrast, I would prefer .BIZ for real estate domains with a connection outside of the United States (i.e. belgiumrealestate.biz) or if it was generic (i.e. vacantland.biz)