I am renting a mini van next month for 15 days. We're picking it up in Ft Lauderdale and returning MCO. My best advice is just to periodically check the rates for you rental period on a site such as Travelocity. You can do a search for "car rental only" and it checks the rates for about a dozen different companies. I'm not sure when you are going, but if your able check the rates every couple of weeks because they seem to fluctuate a lot. If you find a rate that you like, you don't have to book it through the Travelocity site but instead you can book it directly on the company's website without even providing a credit card. Later, if you find a better rate you can book the new rate and it only takes a few seconds to cancel the old one. If you have a Costco card I also noticed that they have some pretty good rates on their travel website.
The most important thing is to just continue checking periodically. When I started looking for a van about 8 months ago, the rates for my time frame were between $850 and $1200. As of today, I have a reservation for the 15 days for just over $300.
One last thing, be careful about what size of car you reserve. I don't know how big the 5 people in your party are, but when the car companies offer a "full size" car it is usually something similar to a Nissan Altima, which is not really that large. Compacts are even smaller.