I am not comfortable having lastpass logged into my vault for hours or days on end from my web browser. Therefore, I'm always logging in and then logging out. I use the yubikey as a second factor and don't mind logging in when necessary - I just find it annoying that I have to remember to log out - sometimes I forget.
A nice feature for Lastpass would be to have a timeout value for an auto-logout as a security measure. By auto-logout, I mean logging out of the Lastpass vault. A value of 5 minutes to 'never' would be helpful in preventing malware (or anyone with access to my machine) farming my vault of my login credentials and those of my clients (which I store). I hope you will consider this idea. Thanks.