Well... it's not as complicated as you might think Generally speaking I use the Tab button a lot so the spacing helps things to make sense. As for the dreamweaver thing I personally can't stand it! I guess the fact that I've been using HTML practically forever helps things too... but like Zedtu said, it is very much a matter of opinion/preference.
Basically what I meant was that for instance if you have a 3 column CSS layout that uses float and margins and you resize the browser, at some point the layout will [generally] 'break'. What I mean by this is that either the layout becomes distorted, or one of the columns jumps down below the other two because it just won't fit anymore... Anyway, just something I've found from some personal experiences.