Yes, I misused the term "guaranteed," at least as defined in the Marriott Bonvoy terms & conditions.

At non-resort JW Marriott, Marriott Hotels, Delta Hotels, Autograph Collection, and Renaissance Hotels properties: Guaranteed Lounge Access includes an actual guarantee. If the lounge (or an approved alternative) is closed or there is no lounge, then the Platinum Elite (or higher) member + 1 guest get breakfast on the restaurant. In the United States, the T&Cs identify such a breakfast to be "continental," but most properties have traditionally offered a full buffet or a full breakfast. But if the lounge is open, then complimentary restaurant breakfast is not an option. It's not a Platinum Elite welcome gift option as these brands.

At all Sheraton, Le Méridien, and Westin properties: Guaranteed Lounge Access only means that if there's a lounge, then the Platinum Elite (or higher) member + 1 guest are allowed access. There is no alternative and no compensation if there is no lounge or it's closed. Although Marriott Bonvoy calls this Guaranteed Lounge Access, there's really not a true guarantee. However, daily breakfast in the restaurant is a welcome gift option for Platinum Elite and higher.