indireneed,
Excellent letter. I think that no one approach works best. One thing to consider doing is to include copies of the three Guardian articles which tell the UN story very nicely. You might even want to make ref. to The Guardian explicitly in your letter - I don't know.
I suggest this because it is my impression that the UK press and the US press operate somewhat differently. Lots of local US papers, and even larger ones, rely heavily on reports from AP etc. The UK papers also do this but tend also to have more independent investigative reporting of international affairs. So, local papers (apart from local news) tend to rely rather heavily on AP originating stories. Since the Guardian is an internationally known paper, and esp. the Weekly this might help improve the odds.
BEcaus ethe Washington Post is a sister paper of the Guardian and also contributes to the Gdn Weekly maybe that's an angle too.
Good luck,
T.