Personally I think they're the best apartment dogs you could ever have. We live in an apartment.
Why I think that is:
1) They NEVER EVER bark. Most of the neighbors express shock when they learn that "the dog lady" lives right there! They don't even bark when somebody knocks, or even if the maintaince people come right in without knocking.
2) They're very lazy. They require very little activity, and are content to sleep for days. They are nothing like a Lab or other more active "normal" dog. Sighthounds don't leap around and knock things over or bug you with toys to play.
3) A good run every two or three days for about 20 minutes is all they need. Mine are perfectly reliable in just about any open space, and IMO it is mostly training... the Whippet, especially, is bombproof. I practically never leash him. He's very, very well trained and knows many commands and has been all over the world. They are wonderful travelling dogs, and b/c of their low energy level they just sleep on long car trips. Being quiet and mannerly by nature, they don't jump on people or go up to strangers. They don't care about people other than their owners.
All that said, if you want a playful buddy that chases tennis balls and romps with kids, look elsewhere. They don't like obnoxious dogs, they don't like obnoxious children, and they don't like screaming and yelling and discontent in a household. They are noble and peaceful and thrive in a quiet, harmonious atmosphere. They also are not watch dogs. Most of mine I have never heard bark in their lifetimes, only utter the occasional cry if in pain or lonely. They do tend to prefer one member of the family, and ignore others. I like one person dogs, so this appeals to me, but if you want a gregarious family pet, you might be disappointed. Most sighthounds tend to favor the "mom" in the household. They do not do well in kennels, and are picky eaters.
I love ALL dogs, but being a bit of a neat freak (with white furniture haha!) I will stick to my sighthounds
Their names, btw are Monet (Borzoi), Rigby (Whippet), and Lucas is the Grey