You shouldn't need to ask. You should always get it:
Concierge Lounge Access, Platinum & Gold members
At participating Marriott hotels, JW Marriott hotels or Renaissance hotels you will always receive access to the Concierge/Executive Club Lounge during normal hours of operation. For Marriott hotels, JW Marriott hotels or Renaissance hotels not operating a Concierge/Executive Club Lounge, we guarantee you will always receive your complimentary Healthy Start breakfast, Monday through Friday or we'll give you $100 USD. (Not available at resort locations).
http://www.marriott.com/rewards/memb...s/guarantee.mi