Koffee,
I also live downtown. I use the lakefront path, as it seems to be the only sustained route that I am aware of. You can ride consistently on it without having to worry about cars and stopping. People, etc. can be horrendous though. The best thing to do is ride early in the morning. Also, south of Navy Pier is usually less populated.
If you manage to find a good alternative, I would love to hear about it!
Dax