We use gentle leaders and haltis a lot in our service dog training. They're suitable for dogs of any size (though with tiny dogs i can't imagine you would need one)...all they do is lead the dog by the whole head instead of the neck...actually, they're a must for many people with large breeds. I once hurt my shoulder in training class because I had a strong-willed golden puppy that wouldn't walk on leash well (I hurt my shoulder from pulling/snapping the leash). Just like a car, dogs will go in the direction they're looking, and so the gentle leader helps you direct their attention to where you want them to go.
A lot of dogs will do something called "mouthing." That's when they put their mouth around your hand but don't bite down. It is not biting, but instead just a forceful attempt to get your attention and affection. Some dogs will also do it when they're excited and anxious. Still, it's not an OK behavior, if only because some dogs don't know their strength and could hurt a child if they did it to them. Some breeds also bite/nip more, so people should be aware of that. Not every breed is suitable for families...in fact a lot of dogs would be overwhelmed by kids.
Re: hip displasia, I misspoke a little. Yes, it is definitely a problem, I was just disagreeing that it's something you see in every lab/golden. Bigger dogs can have problem with their hips, just as some smaller long dogs have problems with their backs. There are different degrees of it...in some dogs its barely noticable and isn't something that would be regarded as a problem, just something to be aware of so you don't exercise your dog too much. In the ones where it's truly a problem, those should be spotted pretty early on. My friends got a lab a couple years ago from a breeder and found out about six months after they got her that she has severe displasia, to the point where surgery may be necessary. Now, for that dog, her hips are so underdeveloped that I bet the vet would've known before they even bought the dog. Hip displasia was a result of generations of bad/fast breeding in certain breeds, which is why you see it in a lot of popular breeds such as labs and goldens. That is why it's very important to get some dogs from reputable breeders...check references! It's heartbreaking to get a dog with a severe disability that you don't have the money to treat, or that has to be on medication its entire life.
Labs' shedding is a pain in the butt, because their hair is short and coarse. They're the hairs that poke through your clothing and drive me nuts.
At least goldens have soft hair. Yes, vacuuming frequently is a must.