It appears that it wraps all items in an outer div, and each item in it's own div (hence opening and closing double divs?)

Looks like it's answered in http://world.episerver.com/Modules/Forum/Pages/Thread.aspx?id=69955

My issue is it's adding the extra mark up for my <ul> lists:

so, I have

<ul>
    <!-- start block items -->
    <div>
        <!--block -->
        <div>
            <li>{content}</li>
        </div>
        <!--end block>
        <!--block -->
        <div>
            <li>{content</li>
        </div>
        <!--end block>-->
        <!-- end block items -->
    </div>
</ul>

I'd prefer the extra divs removed, but I can see if the css dev cna update his css to display content correctly in that format

You should be able to use customtag and childrentag for this.

@Html.PropertyFor(x => x.Rotator, 
    new
        {
            ChildrenCustomTagName ="li", 
            ChildrenCssClass = "rotator-item"
        })

You could always create a custom content area that doesn't render the divs in live mode  If you only need to do this once or twice on your project then it's a bit overkill and I would go with the usin gthe ChildrenCustomTagName.  I fyou are interested in how to remove the div's via a custom content area I  wrote a blog post about it Extra divs in content area how to remove them ?