Well, with that I can help out a bit more!
1. You wont need an International Driver Permit, as your Drivers License is already in English
2. You should look at each car rental company for the conditions, but a quick check showed the following:
Budget: avoid, as they require a passport for all international renters (including Canadians)
Thrifty: seems good (see below), you have an expiration date on the License, right?
A foreign drivers license* issued by the country of residence of the renter and additional drivers.
*If the foreign issued drivers license is from a country where permanent or non-expiring drivers licenses are issued, the renter and any additional drivers will also be required to show their passport, visa or other current U.S. issued documentation at the beginning of the rental authorizing the renter or driver to be present in the USA at the time of rental.
Alamo/National: depends on where youre going. They require a passport only in some states, but not all of them (California, Nevada, Arizona). If youre going to Florida, youll be OK.
Hertz: seems OK as well
So, if you stick with Thrifty, Alamo, National or Hertz, just book with your Drivers License name, and they will never ask for your passport!
P.S. Im really curious if Alamo will really ask for our passports next month in Vegas! They sure did not in California, even if its required