I have a few places in mind:
Botanical gardens
Bird Kingdom (do they host weddings??)
(on the) Hornblower Niagara Cruise
Wedding Company of Niagara
We are going to have about ~20 people with us (more than I wanted but thats another post...).
Does anyone have suggestions other than these, or have good reviews of these places? I havent been to Ontario/Toronto since 2003!