Both of our dogs were adopted from the Humane Society at about 9 months old.
Ben (shown here at rest) is a australian shepherd/blue heeler cross.

He was already housebroken when we got him but had been put up for adoption because he was a 'little' hyper. We took him to a couple of series of puppy school at Petsmart and worked at socialising him at the offleash park. He's going on 6 years now and is still hyper, still kind of crazy, has discovered random barking as a hobby, inserts himself between me and my wife at every opportunity and I don't even rightly remember when we were just a 'cat only' household. He went through his destructive phase, which was mercifully short, and has full run of the house and our full trust. He's an awesome mutt. He has a bit of an identity crisis though. When he's not trying to be a human (watches tv, sits in chairs etc.) he thinks he's a much smaller dog or maybe a cat. That's when he's either in a lap or lying across the back of the sofa.
Mo. Is a force of nature. She's a Shiba Inu (japanese hunting dog) cross rescue from Louisiana.

She was an uphill battle with training which I attribute as much to the breed as to her time in the kennel system. Very stubborn, possessive, fierce and loyal. We're still working out her destructive quirks after 2 years and have narrowed it down to anything that moves in the backyard and shoes.
When it comes to training, with the exception of non-negotiables such as shitting outside, it's a fair balance of training the dog and the dog training you. A basic obedience course worked wonders, much to my surprise.
Whippets are cool, though a little high strung. My first dog, who moved to Canada with us, was a whippet/jack russell cross and she was the most nimble dog I've yet seen. Somewhere I've got a pic of her standing like a figurehead on the bow of a speedboat at full throttle on Georgian bay.
But I babble. If you want a dog, please research the breeds. Dog ownership is a real responsibility. But it pays back in spades.