My own experience is that the Westin MEL is considerably better than the Sheraton, and the suite I have had at the Westin (on 4 different stays now) was always nicer than the suite I had at the Sheraton (only 1 stay, after that I learned my lesson and booked the Westin instead). The club at the Sheraton is nice but the food is mediocre (nothing wrong with it, but it is lounge food) as are the drinks (poor quality wine, only decent drink was Boags); so it isn't much of a reason for me to stay there. Nor is the location, in a tacky mall (sorry, but there just isn't another way to describe the Southgate complex ... it could have been great, but the developer got too greedy and wrecked it). The Westin's superb concierge has now gone (moved to London) but the staff are still good, esp. if you have stayed there before, and it remains the 2nd or 3rd best hotel in Australia.