just came back from Vancouver i stayed at both the Westin Bayshore and the Sheraton Wall center.
no lounge at the Westin and no breakfast for plats. nice lounge at the Sheraton which serves breakfast (fruits, toast, yogurt, boiled eggs etc.. ) and snacks in the evening ( 2 hot items, fruits, veggies etc..).
for upgrade: my suite upgrade success is 100% at the sheraton and 93% at the Westin ( only one stay out of probably 15 was not upgraded to suite)
for location: I like both. if you want to be close to Coal harbor, English bay, stanley park then stay at the Westin. if you want to be close to Pacific mall and Downtown area stay at the Sheraton. its only 20 min walk from the Westin to the Sheraton and vice versa