WordPress Multisite layout thoughts?

Hello Mighty WordPress MU experts.

I am trying to work with an idea to help me put together a series of multisite blogs, and I am looking to the community for some ideas on scaling and layout.

What I envision is a similar to an national firm that has 3 people in 3 cities. each person would get a blog…

What I want it

coolfirm.com/vegas/john

coolfirm.com/vegas/jw

coolfirm.com/vegas/abc

coolfirm.com/nyc/jack

coolfirm.com/nyc/todd

coolfirm.com/ohio/sally

coolfirm.com/ohio/sax

I looked at WordPress Multi Network, but I am concerned that it wont work, or work for a while, or break other things.

How would you handle this.