Your content deserves the best. The site should conform to your content, not the other way around. WordPress comes with a full theme system which makes designing everything from the simplest site to the most complicated portal a piece of cake.
WordPress has killer search baked in. Every word you write is fully searchable through a single box at the top of each page and if your users choose to use an external search engine like Google, rest assured, WordPress will present your content in a way that all but ensures it makes it to the top of the results every time.