This is a very useful set of plugins that I've used for years: http://yoast.com/tools/seo/disable-pers ... ch-plugin/
Notably, I always make sure I have:
Install for Google.com (disabled SearchWiki too)
Install for google.com with American Adwords ads
Install for google.ca
Obviously .com and .ca go without saying. If you're doing U.S. adwords work it's also useful to have the ability to view the actual American adwords results.