I asked this same question a few weeks ago and I was glad to get the advice to stick with clipless (I have run clipless on all my bikes for the last 4 years or so).

You can get SPD's that don't look out of place on a road bike (I'm happy with my PD-A520's), and wear MTB shoes with a recessed cleat that are fine for a few miles of walking around downtown.

Clipless + fixed is a match made in heaven - you have this visceral direct sense of connection to the bike and the road, plus it's very nice to be able to enage different muscles when doing a long climb without the option of gearing down or coasting to rest for a second.