As an FYI, it looks like the 802.11n final spec, will finally be coming next month... http://www.engadget.com/2009/07/21/802-11n-should-go-final-by-september-just-when-its-starting-to/
Just something to consider as new or updated products may be released (though I don't know if there will be any significant difference from the current n draft to the finalized version).
As far as range is concerned, there is always the standard "varies on multiple factors" statement. And I believe the n standard is more focused on throughput than range.
My advice, see what the individual brands are claiming and try to research (i.e. Newegg reviews) if they're accurate.