My own experience has been mixed. When plat perks were not offed, I simply asked "is the CL open?" or "are rooms sold out on the executive floor?" Most times I did not need to say more and they would wake up and offer upgrade and lounge access.
It is not a good practice for the hotel not to treat its best customers in a hospitable way.

The CL at SF Marriott is small to begin with, even on non-convention days, the place is usually packed. In fact, I would prefer to having breakfast coupons (on weekends) instead of lounge access. The breakfast buffet is outstanding!