In a related discussion on WebmasterWorld about the Google Keyword Tool...
Google Keyword tool - Showing very inaccurate data http://www.webmasterworld.com/google/4200253.htm [webmasterworld.com]
...tedster quotes a comment from a Google employee on Google's Adword Support forum that's relevant here.
If you use both the previous and updated versions of the Keyword Tool to search for keywords, you may notice differences between the tools for statistics on Global Monthly Searches and Local Monthly Searches.
This is because the previous version of the Keyword Tool provides search statistics based on Google.com search traffic AND traffic from search partners, while the updated version of the Keyword Tool provides search statistics based on Google.com traffic only. We've updated these statistics based on user feedback, and hope you find them helpful for keyword selection.
[google.com...] [emphasis added]
I had used the previous Keyword Tool interface for the search frequency information I cite in posts above. It's clear now that the adjustments Google made on Suggest just before the launch of Instant were to bring it in line with the new Keyword Tool numbers. And these new numbers dropped the search partners, I assume because... to mesh with the Instant autocomplete algo... Google needed numbers that would reflect searcher behavior that was closer to the actual searches on the specific google domains themselves.
The new numbers are pretty much in line with what we're seeing on Instant, and I think also reflect the kind of localization I was describing, though the new search numbers reflect that localization as well.
Re singular/plural... instead of, say, a 9 to 1 predominance of plural vs singular for some of the terms I'd noted in the old Keyword Tool, in the New Keyword Tool there's roughly a 2-to-1 or 3-to-1 preference for the plural "hotels.
The Paris Hotel Las Vegas is much more predominant search from the US than the previous numbers had suggested.
New Keyword Tool - Local Monthly Searches in US...
paris las vegas - 27,100
paris hotels - 9,900
paris hotel las vegas - 8,100
paris hotel - 5,400
Instant suggestions on Google.com, in US, from SF Bay Area...
paris las vegas
paris hotel
paris hotels
paris hotel las vegas
New Keyword Tool - Local Monthly Searches in UK...
paris hotels - 14,800
paris hotel - 5,400
paris hotel las vegas - 1,300
paris las vegas - 1,000
Instant on Google.co.uk (with a list of 5)
paris hotels
Then, for "paris ho"
paris hotels
and, further down the suggestion list...
paris hotel las vegas
Note that "paris hotel" singular wasn't suggested on UK Instant, at least not on a list of 5 that I saw.