Sounds like a fund trip! St. John is busy this year with visitors who might normally be in cruise ships or in other COVID-restricted spots. It is worth getting reservations at must-visit restaurants; many are reducing hours due to lack of staff and staff fatigue. You should expect some summer restaurant closings, even with a crowded island.

Windmill Bar is great. There are also more local / West Indian options than in the past; I pulled together a Google Map to show those options - https://www.google.com/maps/d/u/2/edit?mid=1SE5oaKMkzyghwt4DDSGhjpSzNkS39FWQ&usp=sharing

Cheers, RickG