I have a pair of Dr. Martens http://www.drmartens.com/ . They are slip ons a (no laces). They are very light and comfy ehoough to change terminals bu foot in LAX or LHR and are generally good enough for a suit but not a tux.

They also do not contain a metal strip re-enforcement thinggy so you can keep them on through security on countries other than the US.