Thats totally a design decision you'd have to make based on your users. Generally if I have only three dashboards I'd like my users to access I'll create a simple app and restrict them to that app. The "landing" page on the app would show some "summary charts" and then have text directing the users on how to navigate around or what the values/options/charts all mean. Then instead of a drop down list (because you only have three dashboards) just add the view's to the navigation bar as their own clickable tab.
