In EPi 7 the ContextMenu has been replaced by the QuickNavigator. To render it on your page add @Html.RenderEPiServerQuickNavigator(). Most solutions have this added in the root layout. But in your case I would have a root layout with out one and then a second layout that renders it. That way you can let the pages you don't want to show it on inheret from the root layout and the others from the second one.