DAYTONA BEACH (DAB)
Just 30 miles from St. Augustine, DAB is the closest airport - a convenience for which you can expect to pay extra. More beach time, though?
JACKSONVILLE AIRPORT (JAX)
Slightly further away, JAX is approximately 75 miles from St. Augustine but it's an easy highway-drive down US 95. As a bigger city airport, it's simple to navigate and is a destination for low-cost carriers like Air Train, Southwest and Jet Blue. You're likely to get a good car rental rate as well.
ORLANDO AIRPORT (MCO)
Arrive at MCO from just about anywhere - this is the biggest airport in the region, so you might get both a direct flight and a good rental car price. That said, it is a longer drive to the coast - about an hour and a half, or 95 miles.