Originally, I thought I had a solid choice between Amazon-CreateSpace and Lightening Source. But, I’ve come to realize that for first-time, self-publishers, there really isn’t a choice. While Lightening Source, via Ingram Spark, represents an opportunity to publish on an international scale, across e-books and paper copies, the predominate opinion in the industry is that the retail stores and major outlets will not purchase an indie paperback. They want to contract with a company, a traditional publisher. Amazon’s pricing model is also at odds with traditional publishing prices, which creates friction between the two approaches to the industry. (Follow the Hachette-Amazon court suit.)
So, as a self-publisher, trying to get noticed, your best bet is to stay with the “big dog,” Amazon. You can add your paperback versions through Amazon’s print-on-demand (POD) company, CreateSpace.
I believe that your pathway should be to start with Amazon and get noticed. Once your marketing has built your customer base sufficiently, you might receive offers from a publishing house, who can distribute your book through the major retailers. It will take time—marketing and patience.