I use category and then postname, but I think whether or not you include categorie depends on the type of blog you have, and how many posts a day you make.
actually i prefer using .html as page extension rather that a /folder/ some says it has a SEO effect depends on how you work on your SEO stuff
Personally, I love using extensionless page names. Every folder that has a default document in it can be referenced as /folder/ or /folder/index.html (assuming index.html is the default document). Google and the engines could careless which you choose. That is the whole purpose of default documents like index.html, index.php, default.asp, default.aspx... so that you don't HAVE to give a file name and can use the folder name instead. The search engines have been dealing with folder names that render pages forever. If it were a problem then most sites' home pages would be an issue because most use the root folder '/' instead of the actual page name '/index.html' or whatever it is. The extension does not provide any SEO advantage. Have you ever looked in Google WMT at the link text they see in your inbound links? Have you noticed what "link text" they see when someone links to you with a URL as the link text like http://www.example.com/folder/page.html? The link text they see is "http www example com folder page html" which makes total sense because they probably always normalize the link text (and title, h1, etc.) before evaluating it for keywords by replacing all punctuation and special characters with spaces. So if anything, having an html extension would probably hurt you a tiny bit instead of helping you since it adds an extra word to the URL reducing the keyword density of other important keywords within the URL. I would go with /%postname%/.
One of Michael Gray's articles thoroughly explains the best permalink option: http://www.wolf-howl.com/seo/url-configuration-wordpress/