Check if GF will provide Hotel accommodation for the day.
Usual rules is that if a connection is over 8hrs, the airline should provide accommodation.
As she is flying business, the even more of a case !
If she has a hotac, advise is to get some rest (the overnight flight is only 6hrs) and head for the tourist sites (2 hrs in a taxi is more than enough), before a afternoon tea at the Ritz Carlton and then back to the airport for the flight.