Travelling on the carnival legend may 23-31 to the eastern caribbean

the ports of call are San Juan, St. Thomas, Tortula.

Do I take the ship's shore excursions, or go on my own during these stops?
any recommendations as to what tours we do are also recommended.

It's usually safer to book via the cruise line, but you will get a better deal looking at tours that are offered separately on the Internet. In that case, I would advise that you book any independent shore excursion with some other people to fill out your party. St. Thomas can be scary at times.

Sometimes, the best tours are offered by cab drivers. Work out a price before you leave.

Have a WONDERFUL trip!