How many frequent flyer miles does it take to get to Orlando from Medford OR?

I really want to go to Harry potter world in the fall of 2012 and I wanted to know how many miles it would take to get from Medford, Oregon to Orlando, Florida with a family of four or three. I just wanted an estimate for both ways, non refundable tickets. And would it be cheaper to buy them with the miles now or would it matter? It doesn't matter what cl or seats but no first cl please! Thanks for your help!