Diamond Ambassador here. My wife and I just returned from a two-night stay at the IC Times Square NYC. Chose the breakfast amenity at checkin. We were handed two breakfast coupons at checkin, one for each morning. The coupons both explicitly state that tax and gratuity are included. At breakfast each day the server took one of the coupons and we both ate from the buffet (which has room for improvement, BTW.) Never saw a check, and nothing has appeared on the final bill that is in any way related to the breakfasts.