Here's a thought- since you're used to riding BMX, why not look at getting another one for commuting? Possibly one with 24" wheels. Single speed, nimble and agile handling. My avatar is my primary commuter, but I have used my 8 yr old son's Haro H-1 BMX with 20" wheels from time to time- and I'm 6'.
If you go the BMX route, then you'll probably want to upgrade the braking system.