Hi Mike

It's really hard to kind of say how to write this out without the target html I think... but I'm wondering if this gist helps you on your way ?

Basically you get your product page, and then you can iterate it's children, then each of those children have children, so on and so forth:

@inherits UmbracoTemplatePage
@{
    //top Blue menu
    // need to find producter page

    var productSectionPage = Umbraco.TypedContentAtXPath("//productSectionPageDocTypeAlias").FirstOrDefault();

    // get the children of the product section page, eg the product types

    var productTypes = productSectionPage.Children(f => f.IsVisible() && f.DocumentTypeAlias == "productTypeDocTypeAlias");

    // so now we can build our blue to menu by looping through the productTypes and see if they have any products listing, eg whether to shwo the dropdown or not
}

<ul class="nav navbar-nav">
    @foreach (var productType in productTypes)
    {
        // get the products
        var products = productType.Children(f => f.IsVisible() && f.DocumentTypeAlias == "productPageDocTypeAlias");

        if (products.Any())
        {
            <li class="dropdown">
                <a class="btn btn-default dropdown-toggle" id="[email protected]" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true">@productType.Name <span class="caret"></span></a>
                <ul class="dropdown-menu" aria-labelledby="[email protected]">
                    // list products
                    @foreach (var product in products)
                    {
                        // get the categories
                        var categories = product.Children(f => f.IsVisible() && f.DocumentTypeAlias == "categoryDocTypeAlias");
                        if (categories.Any())
                        {
                            // write out categories
                            <li>
                                <h2>@product.Name</h2>
                                <h3>Categories</h3>
                                @foreach (var category in categories)
                                {
                                    // get the brands
                                    var brands = category.Children(f => f.IsVisible() && f.DocumentTypeAlias == "brandDocTypeAlias");
                                    if (brands.Any())
                                    {
                                        <h2><a href="@category.Url">@category.Name</a></h2>
                                        <h3>Brands</h3>
                                        foreach (var brand in brands)
                                        {
                                            <a class="@[email protected]" href="@brand.Url">@brand.Name</a>
                                        }
                                    }
                                }
                            </li>
                        }
                        else
                        {
                            <li>@product.Name</li>
                        }


                    }
                </ul>
            </li>
        }
        else
        {
            <li><a href="@productType.Url">@productType.Name</a></li>
        }
    }
</ul>

but obviously you tweak the html to be how your dropdown megamenu should be written out...