You know it's important to do periodic maintenance and upkeep on your property between tenants, but don't take long-term tenants for granted. If they've lived under your roof for a number of years, ask if there's any paint that needs touching up, or how their shades or blinds are holding up. Things wear out and show signs of use. Even if your tenant says everything's fine, she will appreciate your thoughtfulness. Moreover, it will be remembered.