After 25 painful rentals in Louisiana I have finally qualified for PC for the first time. I have a question regarding the best way to maximize my chances of an upgrade.

My wife and I will be renting a car in MIA in July and driving to Key West. I have done this drive on a number of occasions but she has not.

What is the best way of maximizing my chances of an upgrade to a convertible or Prestige car while paying the lowest rate?

Does it matter if I rent a midsize, compact or full-size or will they bump me up to the best available regardless of what I rent?

Has anyone had experiences with the MIA Hertz folks, specifically on the weekends? Do they have decent inventory on the weekends?

Thanks!