I had a Great Dane who had been a puppy mill dog before getting used up and dropped off at the pound one day. She was a fawn colored one. Her name was Freya. She weighed only 80 lbs when I got her and when she died a year and a half later, her weight was up to 110 lbs but she was still underweight. They eat an incredible amount of food.
Our vet said that Danes are prone to osteosarcomas--what Freya eventually died of--and puppies need supplemental calcium as they are growing as most dog foods don't have enough to feed those growing bones.
I would love to have another one, but they do take up a lot of room and those tails will break anything they come into contact with. They are not as cold-hardy as other breeds. However, Freya was very protective of me without being aggressive toward others. She would always keep herself between me and anyone else.