Regarding overture suggested terms – that research tool seems like a good idea, but just think of all the webmasters searching for their terms (it infates the results.)
Google has targeted highly competitive terms/phrases – whats does this mean? Well take a look at the number of adword ads on your SERPS … if your pages arent stuffed full then your terms arent that competitive. In other words google would have nothing to gain by starting bidding wars for those terms 