Since we aren't sure how multiple characters will be working are you planning to have multiple ships for many specific purposes? In most, more traditional MMOs, you can start multiple characters. So I'll have a healer, tank, and dps or 2 for when I feel like swithing things up. Sure, one will be my main, but the others are always there.
In SC it seems that wont be an option. Perhaps you'll need multiple accounts if you want to be a pirate on one, and a Citizen on another. I'm not sure how I feel about this, but think I'll be ok just staying mostly on the side of the law with my character. But I'll still get bored if I'm only flying missions in one ship.
My current ship plan is:
Constellation - exploration missions, shipping a lot of cargo, and flying in groups when my friends might want to join on my ship. I also hope that this ship will allow me to solo a bit more out in the open galaxy to find new things.
Hornet - straight up dog fighting. I probably wont be a huge dog fighter, but I'm sure there will be times when I'll want to just go shoot things. This ship will also be for me to help escort my friends when they are doing their own shipping missions.
M50 - still not 100% sure how will work, but I'm really hoping that this ship will be able to be my spy / scout. I'd like to use it to follow other ships and gain information on their mining / shipping / etc. routes either to sell to competitors, or for my guild to use.
So what's your plan? Include ships you do have, or plan on getting once the game comes out. How will you have 'alts' when you have only one character to play?