Flying LAX-DOH-SIN, arrive DOH 21:55 and depart next day at 09:55. I'm guessing the tour is a no-go with my limited times.
Any other suggestions? My return trip has longer layover so I'm using the +Qatar free night on that overnight (Hear the IC Doha The City is the place to stay but also considering Marriott Marquis due to Plat status).