In January I posted a query concerning whether my wife and I would have access to concierge lounges in full service Marriotts when we traveled as part of a package tour. I am current and lifetime Platinum with Marriott. Some responders thought it was a good question as they too were traveling as part of a tour and a Marriott Hotel was part of their package. The best advice was to let the front desk know on check-in and "see what happens". We stayed at the Beijing Marriott Hotel City Wall and the Renaissance Shanghai Yu Garden in September. In both instances I was immediately offered a Platinum welcome gift and assured that I would have access to the concierge lounges. Both were worth the effort. A quiet place to have a glass of wine or a plate of desert before retiring. In addition, the Shanghai Renaissance upgraded our room to a suite. Our room had a spectacular nighttime view of the Bund. A memorable trip made even more special by the staff at the Beijing and Shanghai Marriotts.
If a package tour includes a stay at a Marriott then effectively that hotel has been booked via a 3rd party agent. Although not a qualifying stay for either points or nights, if a gold/plat member shows their card or proves their status the hotel should grant elite benefits.
This counts for presents too. My sister gave me a voucher for a weekend b&b stay at the Paris Rive Gauche hotel. Upon arrival I advised them of my gold status and was upgraded to a concierge level room and given access to the exec lounge and free internet.