One pair for both dress and casual for me. A black or brown dress shoe that works for my dress slacks works fine with jeans as well.
Because I'm often out until 10 pm with clients, and up at 6am to make the next meeting I no longer carry running shoes, only a pair of flip flops on the off chance I have time for a visit to the pool.
On the dress shoe side, I no longer buy expensive dress shoes, as travel is very hard on any shoe. I'm all for lightweight dress shoes, such as Bostonians for example. I don't mind purchasing a new pair if something happens to the existing pair. In fact something about me and airline seats does more damage to my shoes than anything, as the underseat area even in first has lots of sharp objects that I always seem to catch.
So with that, lots of inexpensive shoes you can replace every few months, and with that distract the client with a nice pair of slacks, shirt, and and maybe even a decent Citizen watch.