Cityscape is a book that I own, but I think I've read it maybe twice since buying it, and I completely missed Urban Savant. However, I disagree that it's especially easy entry. It's got the nice bit of not losing the caster level until level 10, but warlocks don't get any of the three required knowledge skills, nor do they get bardic music. Educated would probably be required to make it work, which requires either FR or EB material. Still, it's a good class despite those caveats, so I'll write it up.
I hadn't thought of prestige bard, and there I have less excuse since I do use UA. But the Perform 8 req is going to throw a wrench in any plans. It's late and my brain isn't working, anyone have a better way of getting Perform as a class skill besides the Apprentice feat?