I've been in this same situation a few times. Get the late checkout around 2:00pm. The front desk will hold your luggage for you. Then I just go to the gym, work out, get a massage, nice shower, change of clothes (bring a small bag with you), then hang in the lounge and surf the web for a couple hours and off to the airport. You can also wander around orchard and shop. Very easy way to spend a day.