Personally I like to create clean HTML / CSS sites that are very easy to manage but are not that scalable and require a lot of efforts to maintain content if your site grows fast.
I go with Flash Sites. Definitely, managing HTML/CSS sites is easy, however, I find Flash more attractive. Any visitor can spend atleast few minutes looking at the way website is designed.
There is nothing better than a clean HTML / CSS web site. But nowadays you really need to have some serious coding if you want to achieve better results with your site.
Now a Days there are many technology and tools are available for the construction of websites. And HTML/CSS, Dynamic or Flash Sites Asp.net, JAVA etc are popular tools for the website creation and you can choose any one form them but the basic design can be done by the HTML/CSS ... It is the most easy way to create a website design and then you can use more advance technology combine with these all.