From what you are looking for I see that you don't mind a large shaggy dog. With a dog walker they will get the exercise and socialization, but you would have to do a lot of training also. You seem to want a playful dog. I was going to recommend a chow, but a chow won't play much. A St. Bernard, bernese, or newfie are good for the qualities you are looking for. Have you looked at the briard, bouvier, or otterhound? It sounds like you want a serious working breed that will take to a daily routine. The dog walker sounds great, but you will also need to provide some exercise. Also with some larger breeds, though they are meant to work for hours, will not like three consecutive hours of midday walking or playing when the weather is hot.