See, now this is where people seem to suffer the greatest confusion, in my opinion. They look at the Tools panel in VS/VWD and see all these marvellous Panel Controls/DropDownLists/ListBoxes/GridViews etc and completely forget, or are oblivious to the fact that every single one of them renders as html.
A fundamental understanding of how these things render is crucial, as is an understanding of the CSS box model, and how to apply it to block level html elements. A "panel control" is just a straightforward div. What I termed earlier as a #wrapper is a div with a width set to whatever I want to constrain the page content. If you style the resulting div rendered by your panel control with a width attribute, you have effectively used a wrapper. You can do this from a style sheet or using inline styles. I prefer a style sheet for cleaner separation of presentation and content.
Basically what I'm suggesting is instead of looking at your page as a collection of panel conrols, datalists, imagebuttons etc, you should think of the html that needs to be used to render your page in the way you want it. Then you can best decide which artifacts in the Toolbox will result in what you want. The only real difference between the ones that appear under General, and the ones that appear under HTML is that the former automatically acquire a unige ID name and runat="server", so they can be manipulated in your server-side code. Once they appear in a browser, they are identical to eachother.
Does that help focus things for you?