I live in Maryland and have Nextel service...I emailed them and asked if I could temporarily change my Direct connect service to be used in Disney...they said it was possible....sounded like a bit of a hassle for me for just a few days. So, I'm probably going to get FRS to use there.
I see you live in Florida, so your service may already work there.
If I were you, I'd call Nextel customer care, and ask them...you certainly can't be a first person to wonder...and I'm sure they'll know for sure.