Some sites have the "Remember me" option checked by default and I believe this is a mistake. If I prefer to log in every time I access a site, I shouldn't have to uncheck this option every time. For those people who select "Remember me" it should be quite some time before they have to login again and select the option again. Also, I think people should explicitly set "Remember me" as it is telling the site that you trust the current computer you are on, and it is safer to assume that the current computer is not trusted by default. Lastly, if sites are smart they should be able to tell if the current browser previously had a "Remember me" cookie set and perhaps default the option to on if it was previously set.
Vox.com and eVite check the option by default.