I would go get a nice pair of sneakers. Maybe get a black pair so they kind of blend in with your pants and won't look awful with a pair of dress pants. Most sneakers have good support and good tread. Whatever you get, plan to spend more than you normally would.
I know this sounds silly, but wearing support panty hose really makes a big difference in how your legs and feet feel at the end of the day. When I waited tables, we worked long hours and what saved me was my panty hose. It costs a lot more than typical nylons, but it form fits to your skin and massages. TMI, but I recommend cutting the crotch out of them so you can breathe down there, or you may end up with yeast infections. I also wore a thin pair of footies under them so my feet didn't sweat.
Crocs are really comfortable, but they are kind of wide and I think a bit awkward to walk in. Not to mention really ugly.