Advanced content layout in drupal I've been evaluating drupal and I'm at a point where I have my header, footer, and sidebar set up properly. I have a basic page node type and I've created a few test pages. My test pages have been very simple, just headers and paragraph tags. What do I do when I want something more complicated? 

If my client wants a certain page to have text and images split into multiple columns at different points in the page instead of just one how can I accomplish this when the only input the end user has is a wysiwyg form?

Is there a module for this type of thing or does it require knowing in advance how the client will want to layout each of the different pages and make templates for them all?
What you're asking about is usually referred to as "theming", and it is a huge subject.

I suggest you read up on "starter themes", which are Drupal theme projects that are specifically designed for the type of flexibility you want.

As you can see, there are several of these. One that is both popular, well-documented and well-supported is Zen.  Getting a grip on Zen takes some effort (it seems both useless and bone-ugly out of the box).  But Zen, together with one of the avialable grid frameworks (Zen Grids, 960.gs, Gridset App) gives tremendous flexibility.  It is well worth the effort to get to grips with.