I would look at using Shimano SPD pedals (M520 or the road version with additional support A520) and a Shimano shoe with the "RT" model prefix. I used RT-80's with the old, original Ultegra SPD road pedals (they don't make them anymore, but I think they were the best road pedals ever made) for last year's Paris-Brest-Paris on a fixie, so they'll handle all day riding as well as walking. The RT-80's are basically a mountain bike shoe without the lugged sole, so it looks more like a road shoe (if you're concerned about that sort of thing - I know I am!). It takes SPD mtb cleats, recessed into the sole. This should allow you to walk thru the warehouse without looking like a duck until you get to where you keep your normal street shoes. They also use velcro and ratchets for tightening instead of laces (I just HATE laces!), and if the ratcheting mechanism wears out, they take Time ratchets if you can't find the Shimano ones.

Luis