Hi, Scott! We tried Sharepoint. It didn't work for us, because of the reason you name: The only tool I found helpful for me in managing several projects is wrike.com. The usability of this tool greatly depends on your ability to organize things. We started from a blank workspace, but now our structure of groups helps us to keep track of requirements, plans, bugs and reviews for multiple projects in one place, categorized in the way that fits us. You basically need to reflect your workflow in group names. Wrike allows you to apply multiple hierarchies to the same items, so another dimension in your model would be projects and WBSes.
Darell