By James Robbins
Diplomatic correspondent, BBC News
The summit was opened by Queen Elizabeth
The Commonwealth went into this Heads of Government meeting under attack as being irrelevant to - or even unknown by - many of its citizens, particularly the young.
This summit certainly raised the organisation's global profile, and may have won it wider respect.
The decision to grasp the overwhelming global challenge of the times - rising temperatures and climate change - and to invite high-profile leaders from outside the organisation had a lot to do with that.
The appearance of French President Nicolas Sarkozy, the Secretary General of the United Nations, Ban Ki-moon, and the Danish Prime Minister, Lars Lokke Rasmussen, made this look much less like an introspective English-speaking club.
The organisation played to one of its strengths - as a microcosm of the world, an association spanning the developed and the developing world in every continent.
It may never be possible to say how much the "Port-of-Spain Climate Change Consensus" affected whatever emerges from the UN Copenhagen negotiations during December.
However, the leaders here certainly believe it could make a difference.
That is partly because the declaration on the global fund, which would transfer billions of dollars from rich to poorer states after any climate treaty is agreed, let developing countries see some serious money in prospect.
Carbon dioxide emissions were high on the agenda
That could ease the deadlocks between developed and developing world over money and responsibility which have proved such an obstacle to persuading all UN countries to accept some limit to future greenhouse gas emissions.
That limit could be a significant cut (for the historic industrialised countries), or a verifiable reduction in the future rise of their emissions (for the emerging and developing economies).
The decision to admit Rwanda as the 54th member dismayed many human rights organisations.
But the few Commonwealth governments initially holding out against welcoming Rwanda at this stage in its political development after the horrors of the 1994 genocide eventually bowed to the majority.
Admitting another country with no strong historic links to Britain - Mozambique was the first - may broaden the base of the organisation, although some see it as a dangerous dilution.
Jury out on Zimbabwe
The Commonwealth avoided any decision on Zimbabwe. The heads of government "looked forward to the conditions for the return of Zimbabwe to the Commonwealth".
That makes clear that the jury is still out on the durability of power-sharing in Zimbabwe, and is certainly still out on the return to good governance and guarantees of human rights.
Among all the other issues discussed, where to hold the next summit was a potential stink bomb threatening the carnival atmosphere in Trinidad.
Many governments were shocked that Sri Lanka was, for months before this meeting, the only candidate to stage the next meeting in 2011.
The 2015 meeting will be held in Mauritius
Australia stepped forward as an alternative venue and was gleefully seized upon. Sri Lanka was given the consolation of 2013.
But, imaginatively in the view of many, Mauritius was awarded the 2015 meeting.
It leaves open the possibility that Mauritius could still be brought forward to take Sri Lanka's place if, as the date approaches, there is no stomach among leaders for going there.
Many in the Commonwealth, including some - if not all - of its critics, seem to be concluding that the organisation did itself some good in Trinidad and Tobago.