I haven't played much yet but my most successful game is as Brandenburg (started in 1630 i believe) where I control most of Protestant Germany as well as Eastern Prussia, Silesia, and Ratibor, 3 colonies in alaska (two with golds

) and a pretty big colonial empire in Louisiana, Texas, Alabama, Mississippi, and the Great plains. I have Saxony and Sweden as vassals too.

The only problem is that this all took me nearly 100 years to get, cuz I had to get myself as HRE and sign a few alliances in order to stand the slightest chance against Austria. Now I have about 50 more years to go to try to unite the rest of Germany (Catholic parts mostly), and a lot of it belongs to France...