St. Croix is definetly worth a visit but so much to do and see in only one day. I guess it would give you a taste to then plan a longer return visit. Sept would likely have some closings. I have never been there in that month. You could maybe take a look at
www.gotostcroix.com to get a feel for that. I am guessing you could take an island tour or rent a car yourselves to do that or could spend the day walking Christiansted.
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