I'm really active on a Lab board and have lots of friends with Labs. I would NOT recommend a Lab as an apartment dog for a single person with a busy life. Besides being high energy, Labs take a lot of training commitment in their first three years, a lot more than people realize. You see service dogs and think "yeah, that's the kind of dog I want"- but you have no idea the intense amount of training it takes to get there.
I got involved with this Lab thing because my Earnest is Lab and Dane, and at 7 months old he was such a handful I thought he had some serious problems. He was so awful I was afraid I wouldn't be able to keep him, and I have 20 years experience in the animal business, including rehabbing rescues with behavioral problems. I started asking around and when people started telling me that eating everything in sight, including a mattress, and insane hyperactivity were "typical Lab" I started doing more research and discovered they were right.
Don't get me wrong, Labs are great dogs, but they are NOT easy.
Labs also are very dependent as a general rule. They don't do well home alone all day, they tend to be destructive or develop other problems like separation anxiety.
http://www.lab-retriever.net/board (hope it's okay to post this link) this is a really great helpful group of people, you will find a wealth of information about the breed, enough to make the right decision for you and a dog.
I agree, Danes, although big, are really low energy. I've had Danes in an apartment and with two good walks a day and a lot of attention when I was home they do fine. Thank heaven as Earnest matured he got more of the mellow Dane characteristic
s!