The Marriott Hotel in Quahog is where Ida Quagmire and Brian Griffin meet over drinks and have sex while getting over spats in "Quagmire's Dad".
When Glenn Quagmire becomes angry with his dad for having a sex change and leaving him confused, his dad leaves for the Marriott.
Meanwhile, Brian is dejected because no one is interested in his web publishing seminar and decides to hoist a few drinks at the Marriott himself. While there, he comes across Quagmire's father, Ida, and the two quickly bond. Deciding to go back to Ida's hotel room, the two decide to kiss and have sex.
A piece of stationary from the Marriott plays a key part of Brian's defense of Mayor Adam West in "12 and a Half Angry Men".
Sonja takes Quagmire to the Marriott to fulfill a sexual fantasy of Quagmire having sex with his father Ida while she watches in "Quagmire's Quagmire". As they leave after, the doorman asks if Quagmire enjoyed his stay and he flatly says he did not.