Keep a shovel handy. The poop is LARGE. Never underestimate the ability of a Great Dane to climb onto any horizontal surface to retrieve anything potentially edible.
Don't hang a dish towel from the refrigerator door. Keep an anti-baby clip on the pantry door. Empty all wastebaskets before you leave the house, or keep all access to them closed.
If you are considering getting a Dane, do your research. Think about the the reasons you want this animal. If it's because you want protection, keep in mind they pick and choose who they're going to protect. You will lose friends if you get a mean one. Reason being, Danes are protective, loyal, and extremely territorial, and unbelievably sneaky for a dog that size.
REMEMBER, you have to train this animal, taking into account that it's going to get AS BIG AS YOU in a very short period of time. They learn this, and quickly learn to use their size to their advantage. The bigger they get, the harder they are to train.
They snore like compressors, slobber like fountains, fart like truckers and consume LARGE QUANTITIES OF DOG FOOD. If ya think yer gonna git by with just buyin' Ol'Roy, guess again. They need nutrition, not saw dust and fish bones.
Good luck with your decision.