There is a little-known feature of amazon's kindle books that allows users to find their highlights in one location:
It looks like this when you log in the first time. In the upper right hand corner, you can log in using your amazon information.
Your "homepage" will look something like this:
Once you arrive there, click on the "Your Highlights" link, which will take you to a page that lists of your highlights by book (most recently highlighted first) and in order.
For example, I was reading Dorothy Sayer's Whose Body last night. This is what my highlights area for that book looks like:
You can use the copy & paste functions to quickly add long quotes from your kindle book to your reviews.
Hope this helps!