When you have a CSS layout for a template and you base your top level pages on that template. What's the best practice when you create the level of pages below that? Should those pages just inherit the layout of the parent page? Should they use they're own template? own layout?

I'm having a problem where my sub pages are inheriting the web parts of their parent pages. Including the content areas. So I wind up with all the content from the next higher level page in the heirarchy on each sub page.

How do I avoid this? Am I doing something wrong in my layout? Something wrong in my template? Or something wrong when I create a new page item?

Here is my base layout:

<div id="top-bar"></div>
<div id="site-wrapper" class="interior">
     <a href="template_home.html" id="interior-link">Pinnacle</a>
<div id="header">
        <cc1:CMSWebPartZone ID="MainNav" runat="server" />
</div>
<div id="nav-col">
	<cc1:CMSWebPartZone ID="SubNav" runat="server" />
</div>
<div id="content-col">
       <cc1:CMSWebPartZone ID="MainContent" runat="server" />
</div>
<div id="news-col">
	<cc1:CMSWebPartZone ID="RightContent" runat="server" />
</div>
<div id="footer">
	<cc1:CMSWebPartZone ID="Footer" runat="server" />
</div>
</div>

When I create a page at the top level of navigation and add web parts to each zone as appropriate (like a navigation part to the MainNav zone, etc.), those pages render just fine. When I create a new page under that new page, all the web parts from the first page are inherited?

What am I doing wrong?