Hi Andy,
I like to promote people making more content that is relevant to their business. I always feel that Google likes sites better when they have fresh content. Also, large sites can tend to get more backlinks to the various pages and categories. PageRank is still very important in ranking well.
You can try to segregate your content into separate sections for the major categories of your content and then branch out to all of your categories. For example, if I was writing about cars that would be a top category, and then maybe I would have a subsection for each manufacturer like Ford, Audi, General Motors, and the list goes on. Then I could break the categories down by model for each manufacturer. Then under models, I could have 4 door or 2 door models. The list could keep going almost forever.
Google will understand the structure and give every level in the tree PageRank and authority for its major topic. Because PageRank is generated for all of those pages and as long as they are linked correctly all the way back up to the main index page the whole site should be relevant and move up in the rankings.
Remember you can control the flow of energy by using internal links using specific "Anchor Text" to further control the meaning and relevance of your links. This would be considered "PageRank Sculpting" by most people and is still effective if done correctly.
Try to create highly targeted and relevant content to attract "High Value" links to your internal pages. Also, outreach to relevant sites can help get powerful links that will boost you up in the rankings.
Here are a couple links to articles regarding PageRank that may be of interest to you.
I hope this helps you a little,
Best Regards