Technically, I would say anytime is good considering the alternative is staying at home and going to work.
Minus the smarm, I would say spring or early fall based on weather possibilities. With winter cruises, you do run the risk of the water being just a smidge too chilly for swimming at CC (for example). Likewise, the humidity in the summer can makes thing a little uncomfortable at some ports. Late fall does run you a chance of potential impact during storm season (even if it's just more chop and a possible re-route). Spring is also a better time especially for reduced winds (so you can dock at CC) and lesser rain.