Book waaaaaaaaaaaay in advance and go for a small hotel or bed and breakfast type of place. You may want to rent a car – also waaaaaaaaay in advance and stay just outside of POS. perhaps in woodbrook. It’s small island. when I stay with my auntie in woodbrook I walk to pos.

You can check the following site for accomodations:

http://www.tntisland.com/sites.html#accom

Tip: Go for the b&bs in the surrounding areas like Woodbrook, St. James, and St. Anns. Transportation is generally easy at these locations and they are mere mins away from the capital. Taxi fare is pretty cheap ($4-5TT /$1 US).

And like Kitty said, book in advance.