One liner

wget --recursive --page-requisites --adjust-extension --span-hosts --convert-links --restrict-file-names=windows --domains yoursite.com --no-parent yoursite.com

Explained

--recursive \ # Download the whole site.
--page-requisites \ # Get all assets/elements (CSS/JS/images).
--adjust-extension \ # Save files with .html on the end.
--span-hosts \ # Include necessary assets from offsite as well.
--convert-links \ # Update links to still work in the static version.
--restrict-file-names=windows \ # Modify filenames to work in Windows as well.
--domains=yoursite.com,domain2.com \ # Do not follow links outside these domains.
--no-parent \ # Don't follow links outside the directory you pass in.
yoursite.com/ # The URL to download