I didn't like seamonkey when I tried it (under Win2k), it kept adding html that I didn't want. My pages were pretty simple, so I just ended up using a text editor. I've since moved to Drupal CMS, so now the only html page I have is a custom 404 error page.
If you want to just see the html markup, gedit is good, under >view it gives you different options for highlight mode (i.e. it'll highlight tags and such). Haven't tried Komposer, might be the way to go...