Specialized touring shoes are an amazing option for this. I am really liking mine so far. They are built on their road shoe sole, but with a walking tread instead of the big cleats. These are not the corny lace up type touring shoes, these are the closest thing to walkable road shoes that I have found. They are also easier to put covers than mtb shoes.

Eggbeaters are also a pretty good deal, get them cheap on sale and replace as needed.