If you can skip the US leg (recommended, as by others) and, if you can, extend south into Belize, Guatemala... this is the absolute best time of the year for those areas; later begins the more difficut seasonal cycles: Feb.- April, sweltering heat, May-July heavy rains (and major flooding), then hurricane season 'til about October...
but this time of year most of it is like the Garden of Eden and, if you have time and interest, check out the whole Maya thing; both the ruins and the people... they are wonderful, polite, curious and helpful.
I lived in Belize for a couple of years and loved it... true Carribean living on some of the most beautiful beaches in the world and, within less than an hour, the raw beauty of deep jungle mountains, and the people, the villages, endless back roads... ahhh... note: the

is horrible but the rum is heavenly

... all of this, of course, IMHO