I've used Dreamweaver (albeit CS3 so I am a few versions back), but I am disappointed with the amount of invalid markup it produces.  Are there other WYSIWYG editors out there that produce valid markup?
What is a good WYSIWYG HTML Editor?
html;wysiwyg
If you want control over your code use the code view in Dreamweaver or just a plain text editor like Notepad++ on Windows, Textmate on Mac or Vim on *nix. The problem with WYSIWYG is that you don't have full control over the code you produce, allthough you are free too clean up afterwards offcourse.