I'm going to play Devil's Advocate for a bit. Please seriously consider this.
While I also hate cigarettes, I know that sometimes people use this to battling cravings for other addictions. Basically fighting an addiction with an addiction. The biggest difference is that you can live a normal life with cigarettes that you can't with drugs and alcohol. I think it's awesome that that fest was about overcoming addiction. It might explain why they were so cranky about cosplayers, too. When you're finally getting your life back on track, things that pop up and remind you of your addiction can cause extremely negative reactions. Besides, if they booked the park in advance, I would be a bit irritated to find that it was taken over by something else, too. Not all cosplayers have good behavior, either. I don't like screaming so it's tough to be in certain places when it's nothing but squeals. We haven't been in this location since '07, and they could have started the event at that park since '08. Three years would be a long time to get established at a location and think it a calm venue.
I say as best you can, let it fall like water off your back and hold your head up high. This is your life, and you express yourself the way you want and move on from anyone who looks at you cockeyed or mutters insults. Focusing on it ruins the event. Also realize that a park is a public place, and while you are public, so are the parents with their children in the fountain, the couples on shopping trips at Starbucks, and the people celebrating their victories in their struggle over addiction.
Maybe next year it would be easier to move the Vendors hall into the ballroom where Artist Alley was, move Artist Alley to the Vendor's Hall location, and then separate the gaming rooms near the lobby? I loved how the events were at the Hilton and the Vendors and sit down things were at the Red Lion. I think that worked out REALLY well, but maybe some rearranging would help next year.