Nevermind, figured it out.  Just not using it quite right.  Still learning EPiServer, but loving every minute of the learning process!

Changed my first Razor Template to this:

@using EPiServer.Core
@using EPiServer.Web.Mvc.Html

@model RotatorContainerBlock

<div class="HomeRotatingBanner" data-delay="7">
    @Html.PropertyFor(x => x.Images, new { CustomTag = "ul", CssClass="slides", ChildrenCustomTagName = "li", ChildrenCssClass = "active" })
    
    <div class="applyButton">
        <a href="#">Apply Now!</a>
    </div>
</div>

Now my instead of a div wrapper I get the ul wrapper and the children elements are all li.

You can change the rendering of contentareas with displaytemplates as well. But if you change rendering completly you should be aware of when doing so you need to fix a lot of the edit-stuff that episerver add while inside editmode. This is the case of the extra div. If the div did not exist episerver could not hook to any html-tag. But as mentioned you can change this by using a displaytemplate and do the magic your self by using Html.EditAttributes on your customized contentarea instead.

I always go with default behavior but if needed I use the same aproach you did or alter a specific contentarea by using UIHint-attribute for that specific property.

Old topic, but probably worth sharing. If you want to get rid of enclosing <div> element for content area you can set this before returning view result:

ViewData.Add(RenderSettings.HasContainerElement, false);