I find it depends on the dog. I've had 3 dogs significantly in my life.
We adopted Lady when I was 8 and she was 5 months. Lady is a wonderful dog, a Beagle mix, but she has had a lot of problems. She is extemely protective of us all, and extemely intelligent. I've never met another dog as smart as her. Lady is nearing 16 now, and has mellowed out quite a bit in the last 3 years, but she has horrible anxiety problems which caused her to be incredibly destructive for about 12 years. Before we adopted her from the Humane Society she was badly abused. We don't know all the details, but we do know that she lived in an apartment that didn't allow dogs, so she was cooped up until her existence was discovered by the landlord. When we got her she was not house-trained, and despite our best efforts, she never really was, so even today she still has "accidents" on the floor at night. Now you might say that this is because of age, and I'm sure part of it is, but she also never completely stopped. When we would leave we had to confine her to the kennel because if she was out she would go into a frenzy and destroy things. When she would go into these frenzies she disregarded pain, and sometimes would hurt herself, fortuately never badly. Also, this would go in cycles, 6 months straight she'd be totally fine, and we could leave her out.
She DID NOT like her kennels, though we made them confortable for her. She'd bend the bars on them with her nose. As she grew we got bigger and stronger kennels, and she'd do the same thing. On one she made herself a window she could stick her head out of, and she seemed satisfied with that. She is a master of escape; we call her "Houdini Hound." She's managed to get out of all of her kennels and many, many occasions, even with padlocks. We had to padlock the kennels because it was way too easy for her to get out of them without the locks (we always kept the key near the kennel).
Lady is also an obnoxious doggy, with horrible manners! She's greedy, and tries to "hypnotize" people in order to get their dinner. She'd get me up in the morning, one summer while I was home from school, at 9AM ever morning so I could giver her a Chew-Eez, her favorite. There were usually other people up, but no, she wanted ME to do it. When we were younger, Lady would know when it was getting close to September and close to when school would start up again, and start getting panicky and upset. She also had epilepsy, which is under control now, but that was always scary when she had seizures. Now Lady is old, and just wants to take walks, sleep, and eat, which is exactly what she does!
Scooby was my sister's dog through her boyfriend at the time. He was a Great Dane, and just huge, and very sweet. He tried to sit on your lap. He was a big baby who tried to get in bed with you when there was a thunderstorm. When he wanted to go to bed and thought you should as well, he'd howl and complain! One time he wanted me up in the morning, and shook his stupid flappy ears until I did. He didn't want me up for a specific purpose except to give him attention; my sister was up and downstairs! He wasn't particularlly bright, and a piece of sting in his way would be enough of a barrier to him. Something began to go wrong in his brain, though, when he was middle-aged, and he began to act aggressive and snap at people, which was incredibly unusual for him and his breed, so they decided to put him down. We think there was a brain tumor.
Jinx is now my sister's dog, and she's had her since she was 1 year old. She's a Beagle mix as well, but she doesn't look as much like a Beagle as lady does. Jinx is not a smart cookie, either. One time I left the door open enough so she could get her head fully in and push it open if she wanted to come in. She woke me up at 7AM whining and crying because apparently she didn't know how to push it open (it's not a heavy door). She doesn't like to go outside (she'd much rather be inside with you), even if it's for 5 minutes. She's a bully to the cats because she figured out she was bigger than them. She is incredibly sweet, and has a very submissive personality (not to cats, though). She is also the neediest d**n dog I have ever met in my life! She constantly want your attention. She will whine if you aren't paying attention to her even if she's laying down not even a foot away from you. She will also nose her way under your arm so eventually you have your arm around her.
She thinks she's a human. She tried to use her front paws as hands and will try to touch your face like we do her. So, essentially, you have to be careful that she doesn't punch you in the face! She has a huge crush on a male friend of ours. The way she treats him and wants his attention is noticeably different than our other guy friends. It's adorable, really, but sometime Jinx has to be put in another room because she won't let up on him. Also, annoyingly for me, Jinx apparently doesn't understand the whole concept of body heat, and when it's incredibly hot and the air conditioner is off she thinks it's a fantastic idea to lay on top on me, which she normally doesn't do. Oh, and she really, really likes her Christmas jingle bell collar, and cries(!) when it's taken off.
The whole "alpha dog" in the pack is also very true, but since the adult (parent) is usually the alphas, the dog understands the children are not. This means, in some cases, the dogs will think that he or she is more important than his or her "siblings". Lady always thought that she was more important that my sister or me, and Jinx thinks she's more important than my stepniece! In these cases it's not an agression thing, it's just noticeable in the way they act.
Sorry my post is so long!