This metaphor is referring to everybody's life using a roller coaster. It is trying to say that everyone will have bad times in their life but instead of distressing about it for a long time, you need to get past it as best as you can and enjoy what life has to bring. I like this metaphor because I can relate and instead of thinking about what bad has happened in the past, I think of what good is coming.
This simile isn't really trying to say someones smile is as bright as the sun which isn't really possible and is showing that a girl is happy and smiling. I like this simile because the descriptive words put a good, detailed picture in my head of the two pictures - of the sun and a girl smiling - in a comparative format.
This example of personification is referring to a very windy day when the wind is so strong that you can hear it making a noise that sounds like whistling, not literally howling. I like this example because I personally love the sound of strong winds and it is easily placed as a picture in my mind.
When dogs get excited they wag their tails back and fourth quite rapidly but not even close to fast enough to create a hurricane and this is what the author is referring to, excited dogs that wag their tails quickly! I like this hyperbole because I have actually heard people say this several times before and I think it is quite funny and almost a true statement.