We almost always try to schedule during late August or early Sept. We love that time of the year - most kids in Florida are back in school, and everything quiets down. The one thing I have learned over the years is be wary, and be flexible. I always monitor the long range weather via 2 or 3 of my favorite sites, and we are always ready to pack up and go elsewhere if necessary. mind you that is easier for us, namely because during our Aug/Sept trips we almost always drive to Florida.
All of that being said - we were very lucky this year. We re-located overseas, and decided not to go to Florida this year. We certainly picked a good year to do that.
We have been doing this for 10 years, and only once were met with a hurricane, in 1999 with Floyd. We were at Vero Beach at the time, packed our bags and moved back to OKW. MS were very good at doing the transfer. In fact I remember that the evacuation order was not even in order when we decided we wnated to leave, and MS quickly made the arrangements for us, and refunded the additional points. There was a woman at the desk who was also makign the same arrangements, but decided to put off leaving until 2:00 PM. We left at 10 AM, and took 2 hours to get there. When I went to the store at OKW later that night, (11:00 PM) she was just arriving after a 9 hour drive from VB. Apparently just before 2 - they put up a mandatory evacuation order.