You could also check out the Amara - the hotel itself could use a refresh but it is right in the middle of a vibrant part of Chinatown.

There's also the Copthorne Waterfront which is right on Robertson Quay - a pleasant 10 minute walk to Clarke Quay along the river. And Robertson Quay is better than Clarke Quay for dining/nightlife anyway, it's where the locals go. Be aware the megaclub Zouk is next door so it might be a bit loud on weekends if noise is an issue for you.

No nearby MRT, though I'm sure they have some sort of shuttle bus.