The internet is your friend for helping organize your itinerary of fun things to do on the island! There are countless blogs and websites about the must-see / must-do activities.
We are planning on doing at least one snorkel trip! And maybe a sunset cruise...! Hope to see you there :)
The following websites have some great info:
https://www.visitusvi.com/st-thomas/
https://www.tripadvisor.com/Attractions-g147404-Activities-St_Thomas_U_S_Virgin_Islands.html
https://wearetravelgirls.com/st-thomas-virgin-islands-ultimate-guide/