Marriott has tried to make the system work out so platinum season weeks are higher demand than the gold season weeks. But at some resorts, many of the platinum weeks are of less demand the many of the gold season weeks. As an example, at Newport Coast platinum season is week 23-51 and gold is week 1-22. Weeks 23-37 ( summer) are the highest demand, but the rest of platinum season is generally lower demand than most gold weeks.
The key points is to buy the season which fits you and your family best even if it a gold vs platinum season.