For Mac I use coda and for Windows I realy like Notepad++.
As far as WYSIWYG editors go I`ve never seen one that`s better than
Dreamweaver, wich I`d say it`s not that wysiwyg at all. To be honest
there's no such thing as a WYSIWYG, I think its just a marketing term
that propose a software with a very junky visualization of what your
are doing.
The real deal it's to experience the code rendered in browser (try to
use all of then for production purpose). That`s how your user will
experience it.
I`d also say that vi (or vim) are realy good to work "in server" via
the SSH, I use it sometimes before going to production.
Make good use of plugins such as firebug (firefox) and the google
chrome code inspector.