Gafhyb my dad and I both have a whippet, mine is as described above. Placid, docile, easy going etc. My Dad's a nutcase. I luffs her, but she is an utter fruit loop.
I used to call her Freya the Flying Whippet because everytime I went to their house she would literally fly at my head (out of love and excitement not malice but it's still disconcerting having a dog fly accross the room aiming at your head)
She's getting slightly better now with training and no longer flys but she is still as mad as a box of frogs.
She ended up with my dad because the family who took her on as a pup could not handle her exuberence. I also know of someone at work who sold their whippet pup for similar reasons 
Not all whippets are quiet, there are always those who buck the trend.
If having an easy going dog is important to you, you would be far better off rescuing an older dog whose personality is already known. For terms of ease I cannot reccomend retired greyhounds enough.
I post often about how hard and time consuming dog ownership is. The reality is I love it. I don't find it hard at all. My whippet is very easy. She loves walking but is equally happy to miss her walk and have a cuddle instead if the weather is bad. She's never chewed anything. She house trained like a dream. 99.99% of her time is spent sleeping whilst cuddled upto something living be it the cat or a person. My terrier is a different kettle of fish all together, but I am finding him increasingly easy to deal with. I can see how others would find him hard work.
The reason I stress about how hard a dog is is to prepare people for the worst. You do get high energy dogs who require a lot of work. Sometimes i.e most of the time, people have never owned dog before greatly underestimate just how much they change your life and house. This is why so many end up in rescue. If you can read about all that can go wrong and you still want a dog, great, you will make a good dog owner. If reading about dog hair as a condiment and hour long walks in hailstone and torrential rain and never ending pools of piss all over your house is enough to put you off then you weren't ready for a dog and have had a lucky escape, so has your potential dog who would have ended up feeling resented or in a rescue.
Even when you love dog ownership there are still days when you will wish for your old, simple dog free life. Mainly during bleak winter weather and when your children are ill but the dog still needs walking.
This is about dogs btw. Not puppies. Puppies are hardwork, no matter how much you love them. They're rewarding but they're hard work. Much like a tempremental toddler. I'd happily take on an adult rescue over a pup anyday.