I have decided that I'll start with my Witchdoctor (currently lvl 15) then Swashbuckler (10), Muskateer (10) and finally Privateer (10). Once the Witchdoctor hits level 20, I'll pass off all the gear she isn't using to my Swashbuckler and alternate between the two with my main focus being the WD. Once the WD is 50, I'll do the same with Swash and Musk. This should keep me busy and allow me to experience the game through all 5 classes so that I can better report on all the issues that arise for each class in turn.
As to what I though of the main storyline, having now completed it: it was good! It ended a bit abruptly, but it wasn't a true ending and wasn't meant to be. At this point, we can only complete the first part of the story. I don't know when the next expansion will happen, but I look forward to it!