This is a problem I am facing currently with bigger stage shows where I can not broadcast a live stream feed to screens so the whole audience can see.
You can't go wrong with the classic straight jacket escape (or any sort of escapes for that matter). Granted I'm a little bias since lately I've been developing myself as more of an escape artist but there is so much material you can milk for doing escapology. Escapes will definitely get you to entertain 100+ people.
Other illusions I have been looking at are more on the expensive side that I have been looking to get from a magic shop in my state. They can range anywhere from $1,000-$10,000. If you are on a budget but want to make big illusions at a cheap price, check out any of the material that Andrew Mayne puts out. It's fairly cheap but still plays pretty big. Also Scott Alexander has wonderful material that can entertain big groups of people as well.