Just a few pieces of knowledge to throw out there to help piece it all together.
1 - Everyone gets their own personal story. This is completed by the individual and is varied by race, profession, character creation choices and other choices in game (some that branch far from each other). You can however, have others come help you on your personal story.
2 - no matter what race you are you can travel to the four other capitals after completing the tutorial.
The idea I have is that we each pick a character that we will use only for use with the guild. This may be any race or class, but it may be an idea to coordinate this, so we dont have 3 rangers or something. If these are all different races and classes it would add to an interesting experience.
The other advantage of taking this approach would be that we can each take turns to do some of our story. If I'm away one week, you guys progress and help me out a bit more the following week. If Mick needs to crash out, but others are keen to keep playing, we can - just focus on someone else's story.
If we wanted to just play when the 4 of us are on, then we could always crack out other characters when we only have 2 or 3 and do whatever...
anyways... just some ideas...