For us, the value offering begins with having an impeccably clean house that is properly developed. I used to provide the gift cards and all of that but I didn't find it substantially made any difference to turnover. The reason people stay is because the home is good value, fits their family, and problems are few and far between.
The ability to offer good customer service is a balance at pricing as well. I do not rent my suites at the very top rate I could achieve. I rent it at a rate where I am getting, ideally, 4-5 inquiries a week. That way I have several people to choose from and I make sure that only sell to someone for whom the product fits. Each suite has its own special features. I don't hide my concerns. I had a couple inquire about a suite where one of them was going to bring their brother to the property. I asked if this is really what they wanted because most people would prefer some life separation and there is only one kitchen. For me, it's about genuine care to make sure I see the potential problems ahead of time. I'm not their parents but I want to make sure that I sell a product only to someone who is likely to stay sold for the right reasons. There is no better customer service in my mind then making sure you fit the right product with the right person. It takes 90% of the stress out of PM.
For me at least, my tenants are my friends. I mean they are actually good people that I genuinely care about. When I am at their homes doing whatever little repair I am paying attention to the whole house, the street, and any little thing that might cause them an annoyance. I try to resolve issues before they notice them. I trust them in my homes and I value them as people and clients. Making good housing is more than a business to me, it is a part of my life and I want to ensure this product is something any family would be comfortable in.