What's your layout?

I've been using the Smooth Sailing layout pretty much exclusively since I joined LJ, but I'm thinking about shaking things up a bit. And so, I turn to you, my lovely f-list. Tell me about your layout (especially those of you with header images). What do you use? How do you use it? CSS? Which I don't really understand. Just a custom header code? Which is what I have now. How easy is it? What do you like about it? What do you not like?

Thanks bunches!!