If you find flights to JAX or MIA pricey, consider Orlando (MCO), and get a cheap rental car. This also gives you more flexibility on where you can stay. It's a beautiful time of the year, if any semi-frozen Europeans are tempted to come over.
You're right about the weather Dean. St Augustine is a pretty neat city to visit and not too far. Booked my flights to Jax on Monday. Not sure we're going to see prices until next Wednesday but it would be helpful to know in advance.