I don't like that on my private computer this forum keeps logging me out. DFeed keeps a non-session cookie that is valid for several years. I would imagine that might be considered a little extreme here, given the current option of using a session cookie (although I don't really see how DFeed's policy is different from a mail or usenet client that permanently remembers your account's password). Some sites have a "Keep me logged in" checkbox, and I think that option frequently is documented as allowing up to two weeks to elapse without expiring. One problem with that is that the current layout doesn't have much space to add such a checkbox. What are your thoughts on this? Would you consider increasing the login "stickiness"? If not, I imagine you would accept a pull request to make that optional, right?
BTW, I don't think the intermediate "logged out successfully" page is necessary. For instance, if you log out of forum.dlang.org it just goes back to the forum index, and you quickly see there that you are no longer logged in. How about removing that status page?