If you are flying into Jacksonville, you will want to rent a car. Being the largest geographical city in the continental US, makes mass transportation somewhat difficult to do well. Cab fare from the airport to downtown or the beaches will run in the neighborhood of $50, give or take $10. Rental car rates in Florida are reasonable, especially if renting for a week., because of the competition for tourist dollars in the state. Best rental car opportunities will be at the airport, although there are rental car facilities scattered around the city and beaches area.
If you drive in Jacksonville be aware that a lot of cars do not come equipped with turn signals. This is the single item I noticed and still notice more than anything since my move here. Drivers will zigzag in and out of traffic, changing lanes without notice and barely enough space to move in. Please drive carefully. Have fun, enjoy your visit, but arrive alive!
Jacksonville is known to be the largest city landwise. If you plan to explore our city, I would recommend you renting a car because jacksonville lacks a good public transportation system. If you plan to stay in one area the time of your stay then just catch a cab. But you'll miss out on what our city has to offer.
You can't believe how big this city is--the largest, in terms of land size, in the US. Although there are some shuttle buses that come into town from the airport (which is about 15 minutes from downtown) you don't have a prayer of hailing a taxi from anywhere in town unless you call ahead. Plus, if you're staying downtown (or, more likely if you're here on business, and staying out near the office parks on the Southside of town), you're miles and miles from the beaches and the other places you don't want to miss.
Definitely rent a car, and buy a map.