Information Architecture is more than just menus; it's more about the organisation of content in a clear and logical way. We all know how important it is to produce content that users will find valuable, but it is also equally important to make content findable. Either through SEO, site exploration, through content and of course navigation.
The next logical step after you have conducted your content audit is to create a site map to determine the best structure to present your content.
Your quantitative research should have provided you with some structure in the form of categories, grouping and taxonomies (labelling). If not, it's advisable to define your data set before proceeding.
Having the data set defined like this, you'd want to test how logical they feel for the user with a card sorting exercise to see if the users' group data in the same way that we did.
In our recent project for Mitsubishi Motors, we used a Hierarchical Structure and a subjective organisational scheme. This scheme is used to facilitate learning by assisting users to understand and draw connections between pieces of content. Allowing users to self-identify which audience they belong to and essentially being able to find a relevant entry point from the top level menu items.