The Traveller's Lounge has small rooms you can sleep in. Nominal fee, or many credit cards give complimentary access to it. (My SG Citi PremierMiles card does for example).

Or if you decide against Macau, take an Airport Express (discount fair for sameday return) to the city and walk around. Just in time to go to the top of Victoria Peak for sunset. Take a ferry to TST, see the promenade, and then head on back.