If you just want to get away and relax, then late January and February are good, as well as late September to early November (but then there is that darn hurricane possibility). I've been twice in October, with not a storm with 1000 miles.
I am struggling to make a decision about this very topic. The last 2 years we have cruised in late October to minimize the hurricane threat. We still ended up with bad weather because of one comming or going. While late September was storm free. You can't predict mother nature for sure. It is hard to pass up the September prices though. I must be a hurricane magnet.