I’ve created all kinds of variations with the login form for various membership and network sites. I’ve also seen some really poor implementations of the login forms in plugins. Aside from the fact that I prefer to avoid any third party code, I use the default wp-login.php file to handle user authentication for simplicity. I use a couple functions in to style the form and change the link and heading URLs. I set the login form to redirect to the home page. I add a small icon to the footer menu of the theme so users don’t have to remember the login URL.