Hi Stuart - yes you'll find some skins don't have containers.. and for the free skins I do in particular... some have containers and others don't.. mainly due to time constraints.. and the fact I'm not a great fan of them.
Sometimes you can do things to add colour to containers by modifying the content pane css class or even in the module - setting the background colour.
Containers remind me being a ray of sunshine - Use sparingly or you get sunburnt.
I don't use them on my site - instead I use the tabbed aggregator module - which I did skin/colour in css, and maybe in a few places I might put in one container.
But I have used them effectively on some sites that are quite vibrant in colour.
I've got my free XDContainerama pack on my site - but they are basicly a mix of old containers that are converted to work with DNN 2,3 & 4 sites in some instances, you can use the text/html or images module to create some very interesting affects.
Creating containers is something I like less than paying taxes.. I hate them.. *sigh* strong words but we often take more time making a set of containers that function as we would like, as we take making some skins.. But that's just my own personal thoughts and I do confess... I love seeing the way some skins are designed with the good use of containers.
And I appreciate posts like this that gives further insight to what people are looking for and great to see participation like this too.
Nain Meiers