For longer cruises, remember that there are several hotels/motels around the airport which offer discounted and/or free parking while you're cruising, so long as you stay with them before sailing.
As an example, my friend and I are sailing aboard the
Westerdam on 3/8. We're staying the night before at Springhill Suites (Dania Beach). Parking for 3/7 is $0, for the following 7 nights, $5 each.
Not a bad deal. And the proprty has its own shuttle to get you to and from the pier!
SWR