Answer
The most-popular sizes are 24" x 48" and 24" x 60", both of which are great for any check presentation and group pictures.
18" x 36" is used mostly for children's charities, small ceremonies, or limited budgets.
30"x60" or 30"x72" is the best size for large or important events with press and large crowds. This check size makes a huge impression and is recommended for events where the check will presented to and help by a group of people.