I keep a no-shoes policy which I enforce most of the time. Living in the city, I think it keeps the house much cleaner in general. I keep a metal shoe tray for wet shoes in the winter or when it rains and cubbies for the rest of the time. If someone asks to keep them on, I usually let them and I never enforce the rule if I am having any kind of get together or party because of outfit collaboration with shoes and just because it is too hard to enforce and tell everyone. I almost always take my shoes off at the houses of others just out of habit. I've never thought of keeping slippers in the house because no one has ever objected to going barefoot.