Thanks to everyone for their contributions to this thread. I've been obsessing about this build and finally bought some of the parts for it that I needed. I picked up a nice aluminum single speed frame from bikeisland that doesn't have too aggressive of geometry and a coaster brake wheelset from velomine that was a great deal; Shimano coaster hub laced to Sun CR18 rims. I sourced a chainguard from velo orange in polished aluminum that will compliment the other parts I'll be adding. I'll finish it off with some Shimano a530 dual spd/platform pedals for versatility in dress shoes or cleats. I think once I build it up, it will be a very light and nimble short-distance commuter. The gearing for the parts I have will be 44/18 to start, which I think should accommodate some of the minor hills on the commute. I haven't decided on handlebars yet.
I'll post pictures once I start assembly and try it out. I'm excited to see what it weighs in at when complete. I'm most looking forward to a bike I can just grab and ride in any clothing or any weather.