Hey CoasterFreak.
First make sure you stop in at Dania Beach at Boomers just north of Miami and catch a ride on the Hurricane.
http://www.johnnyupsidedown.com/events05/hr5a.jpg
Miami to Busch Gardens is around 4 1/2 hours less if you drive fast and it is around 280 miles.
Miami to IOA is around 3 1/2 hours and is around 240 miles.
Its an easy drive and mostly all highway some tolls depending on which way you go if heading to Orlando or Tampa.
BGT to IOA is 80 miles.
You can leave Miami around 6 am and be at BGT by 1030am. Do the whole park in one day easily. Stay in Tampa or drive to Orlando that night and hit IOA the following day and sneak over to Sea World and hit Kraken. At one time you could get a pass to hit the different parks or a ticket package deal. Best idea is go to the parks websites and see what kinds of offers they have or any type of ticket specials.
Go here for milage and directions.
http://mappoint.msn.com/