We are family of 6 (inc 2 kids). We will arrive at Guangzhou at about 1am in the morning.

It depends on you.
To stay near the airport, you can have a good rest after the flight journey, but you need to pay for the accommodation for you six and it would be costly to some degree. Actually, transportation would be available to Bauhinia Hotel at that time. It is suggested to reach by taking two taxis and the taxi fare for each is around CNY90.