Louisaho,
If you're getting married in Canada first then you're going to need to look at the logistics of "getting married" again in the US. Please discuss this with whatever coordinator you're using, and make sure he/she knows that you will already be married at the time. Because technically, you can't get married twice. Well you can, but you have to be divorced in between - what I mean is that you can't get married if you're already married. If you're already married then they can't issue a marriage certificate to you in the US, it wouldn't be valid.
What you would instead be doing is a vow renewal.
Also, when booking your flights, please don't book your flight in your married name (if you're taking your husband's last name). The name on your ticket has to match the name on your ID, and it will take several weeks to have your ID changed over to your married name.
There have been way too many problems at the airport due to brides trying to travel using their married names when they don't have ID to match.