Writing a synopsis is an art form in itself. There are those who are brilliant at it - in fact they're better writing the synopsis than writing their manuscript...and then there are the majority who find the synopsis a chore that MUST be done - no matter how much procrastination is put in its way.
Gracie O'Neil's blog http://romanceshewrote.com/ has a fantastic craft piece about writing a synopsis. It turns the art form into an equation that, if followed correctly, renders any synopsis "do-able" and in a very good way.
It also breaks down 'High Concept' into an equation that can be mastered.
At the moment I'm working on my synopsis for the Paranotte Series. This has caused some headaches as I need to work out the right mix of synopsis for the series story arc and also the first book - which is a complete story arc in itself.
Thank goodness for Gracie O'Neil!