I think it's important for everyone to do what works best for them, but you already knew that!
What I do is I offer to bring a dish. That way, I know there will be something that I like and isn't going to kill my plan. I also keep a protein bar in my purse or in the car. That way, if I see that there are no friendly items, I leave the area and have my bar and try to stay focused on my plan. Finally, not to sound like a party pooper, but I stay away from alcohol and soda and just stick with water. Alcohol leads me to bad decisions and soda makes me hungrier for some reason.
To be honest, I can go to a party and be great, but when I come home, I want to binge like crazy due to the deprivation factor. To counteract that, I try to prepare for an outing by saving some calories and then, I eat really clean for the rest of the week, if possible.