So just an update on this:

I ended up going with the All City Pony Express. I was able to find one to test ride, and I just immediately had fun on it. The only surprise is that I ended up fitting on a smaller bike than I expected (55cm vs expected 58cm), but that's all fine and dandy, because now I can share it with my wife if I need be.

Now my only problem is that it looks like my new commute is going to be too short to really cut loose.