I’m sure you know this, but if there is anything specific you want to do, it is wise to verify days and hours of operation, but the Gulf Coast tends to stay warm and functional in the winter, except maybe for swimming in the Gulf.
When we did Normandy, this was in the winter, and the only dissapointment was that the Monet house/museum in Giverny was closed…
When we did our Athens-Istanbul cruise last year, it was in Jan, a wonderful time for the Med. Our intrepid but uninformed friends did a similar cruise in June and was surprised they found themselves melting in Athens, lol. They did not consult us regarding the timing and we were like, “reservations made, well ok, have fun” .
My mother always recommended taking trips around Easter (late March to late April), when you could enjoy spring but avoid crowds.
For several years, she used to take two foreign holidays a year: One, with my father, usually in the autumn, to places of mutual interest that always included culture, cuisine and sunshine, - hence, initially, Spain, then, Italy, and many holidays in Greece, the Greek islands, Turkey.
And then, there was the other: This always took place during the Easter school break, when she headed off by herself with a group of teachers of Classics (who taught Latin, and Classical Studies/ Civilisation - i.e. the history of ancient Greece & Rome) to places of classical interest, (I recall that over a number of years she took trips to Madrid, southern France - Roman Gaul - and Athens, exploring places of importance in classical Greece, among others).
She loved those trips: Not only were the destinations fascinating, but the time of year meant that the climate was congenial (though Madrid in March was surprisingly cold, she recalled, however, she was well prepared for that), and that these places - if popular - were not over-crowded with tourists.
However, above all, the fact that she travelled with a group (the teachers of classics) who were professionally and personally very knowledgeable about (and very interested in) the ancient classical world, meant that the tour guides and drivers they had (or were assigned) were superb, among the best that were available, who knew that they were dealing with very interested, keen and knowledgeable individuals.