The Hyatt has a better location - right in the middle of the shopping district. The Sheraton is a bit of a walk - not ideal if you need to get back to the hotel quickly.

Not sure about the Hyatt suites but the Wall Centre Sheraton does offer fairly large suites - although personal experience (and those of colleagues') suggests it's sometimes a bit of a fight with front desk. Lounge at the Sheraton is average at best, but it doesn't have a lot of seats.