I'm wondering if it might be helpful to know what everybody's character concepts are, and then develop the group dynamic from there. Different alignments/classes/races will have tendencies towards or against types of groups. The city watch/patrol would be good for a group of lawful characters with a lot of faith in the government they live under (breaking that faith might be fun...) Another group of characters might make more sense to be in a thieving crew, or a rebellion of sorts. Then there is always a traveling circus or a gypsy caravan, etc. I guess I'm advocating for a character based group concept.
All that said, I will go first. This is pretty rough and certainly not set in stone, but if we patch together what we have we can put together a balanced party and a really great group concept.
RACE: Moonlit Elf with Fey Heritage (Complete Mage Heritage Feats)
GENDER: Female
ALIGNMENT: Chaotic Good
CLASS: Sorceress - working towards Wild Soul Prestige Class (Complete Mage)
She will be coming out of the trickster/seductress archetypes. Heavy on the illusions and charms. Curiosity and hedonism will cover the fact that she is highly manipulative and has her own agenda. Pledged to the Seelie Court, she will have a benevolent attitude towards "mortals", but her allegiances and will wholly be with the fey and the elves. Tricks and pranks can be very good "life lessons" for the short lived, you know

Of course the Fey Heritage will be more on the secret side, most (if not all) will take her simply for an exotic looking elf.
yadda yadda yadda... GO!