For a work environment, khakis, polo shirt, i would recommend against sneakers or sandals. Opt for a classic simple plain shoe, thin rubber sole (nothing to chunky), more rounded than squarish toe, and minimal bells and whistles.
For loafer something like this Cole Haan with Nike Air:
Cole Haan Santa Barbara at Zappos.com
For a lace up, Clark Desert boots. Classic and in style:
Clarks Desert Boot at Zappos.com (http://www.zappos.com/product/7202394/color/231 - broken link)