I need help from some CMS gurus.. I'm losing my sanity

I'm not a run of the mill computer or web app n00b. I've spent years developing my own custom oscommerce solution, and I'm happy with it as a cart.

But I have a recent need to create a group of small content sites. I have several brands of auto parts that I need to make seperate manufacturer sites for. It would be nice if I could manage them under one roof, but thats not a requirement because I realize it would severly limit my options.

I need a CMS that
-Has hosted\managed support (top priority, I don't have time to maintain a build, protect against sql attacks etc)
-Template support (so that it looks unique)
-Roughly SEO friendly (at least mod rewrite)
-Basic tree structure. I am going to have for instance a Ignition Catagory, then maybe Distributors, so it will drill down to a product and then display information on that product.
-Has a moderate learning curve

I would prefer not using a wordpress or joomla solution as they're usually too cookie cutter. But I'm open to all suggestions. The above requirements are minimums.

Despite all my computer and web app experiance the CMS market is so cluttered and theres such a lack of information that the only place I can turn to is the pros that have spent time with a couple CMSs.

Thanks for the help guys (and girls)

http://www.borla.com/
basically my aspiration, something to this effect.

 

Hands down the best commerce platform is www.magentocommerce.com. It is difficult for beginners to customize and you will need dedicated hosting but it is the future of online commerce. If you're interested send me a pm with more details