Password-Protect Website (Not Just Pages) and Allow Login Page Customization
Right now you have to password-protect individual pages, so if you want to secure the whole site, you have to log into every single page. This isn't practical. Should be able to password-protect the whole website, so that the whole site is behind one login page that a visitor only has to log into once.
Also, the login page is too basic. Should be able to customise it with colors, elements, logos, etc., to match the site, just like you can customize the 494 Error pages.