Two great sites are http://www.shopify.com/ or http://www.squarespace.com/. The both have content management systems that are build and managed by the companies, have integrations with Google Analytics and best of all they have the whole billing flow/system taken care of, which for a commerce site is one of the most important things to get right.
They provide base themes or allow you (with a little elbow grease to learn their respective templating languages) to completely control the front end.
If this is for clients you get the added bonus directing them to the Shopify/SquareSpace customer service for more backend technical questions about payments etc.

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