World of Kulan DM
You could try the urban ranger option from Unearthed Arcana, if a rogue doesn't grab you. Big Tim is definitely the front line bruiser but with flair. @Neurotic has the healer covered, plus there is the cleric NPC with you guys too. So, I wouldn't worry about that.Not sure about what character I want to play. There's a concept of a kobold (possibly rogue) dancing around in my head, but it doesn't 'click' just yet.
Are there any major roles missing that anyone would like me to consider?
I think @Scott DeWar's PC is more wizard than rogue right now, but he's heading towards the Swiftblade prestige class. I'm not sure what @Aust Thale has planned, but I'd say something roguish would be good. The game has been 100% a city-based campaign so far, but there will be some planar machinations.
(Big Tim is already aware that the renegade's lair is a pocket plane that you'll need a planar key for, so there's that to consider. That was discovered by the previous group of PCs.)