Hello Richard,
I think it really depends on your budget. As you are only looking for a 5 months lease, your options might be limited.
For convenience, One Woodbrook Plaza is modern and central. But you might not find m-t-m leases or short term leases for these apartments.
Woodbrook and Newtown are convenient central areas. These two areas, along with St James, have a fairly balanced mix of residential/commercial intermixed.
St Anns, and Maraval are a little more suburban in nature, but be careful of the commuter traffic, as there are limited thoroughfares from or through these areas. (St Anns has a single 2-lane road to access the area).
Westmoorings, Goodwood Park and Diego Martin are a little further out (3-4km) but generally easy access to the city of Port of Spain.
As your stay is relatively short, I would not recommend looking anywhere East of the City. The commute is horrendous and somewhat unpredictable.
Have you contacted an agent to help you find accommodation yet? Is PAHO helping you with this task?
My observations are of course, personal, and I'm genuinely passing on information to you. I hope it helps, and I haven't offended anyone by calling out Maraval and St Anns as being a little less desirable due to the commute.