In February I'd be looking at temperatures along with length.
Now for me coming from Charleston,SC where my temps at home in February range from 50's-70's versus somebody from Minnesota where it is probably below zero, anything in the bahamas will be almost like staying home.
So 5 day, chilliest, 6 day chilly, 7 day at least San Juan should be toasty, 8 day sounds delightful, getting much closer to the equator and warmer temps in February.
If your flying in from up north, any of them would be a nice treat.