i want to go to st marten for a week. should i also go to anguila for a day or two? or go there for a week also?

It all depends on what you like to do and your particular travel style. They are two very different islands. Some people stay on one of the islands and visit the other on day trips. Others split there time between the two.

Look at the entry requirements, that might help with your decision. And how much time you have overall.

Anguilla has stunning beaches & a good dining scene but nothing else. It’s a dry scrubby, scruffy little island. Quiet, not too many tourists.

St Maarten is very touristy, crowded and well visited. French side a bit more gritty, good food, some pretty good beaches, mountainous interior.