One of the minor advantages of ghostwriting is that I don't often have to come up with the big idea for the book. The client has that, occasionally tucked away at the back of their mind where it has to be prised out with a suitably large crowbar, but there nontheless. I just supply the technical ability to write it well.
With my own stuff I am currently suffering from a 'what do I want to write' problem. I have started and abandoned a number of ideas in the last few months, some because they have proved unfeasible, but more because I have simply lost interest. I think, in part, my ghostwriting is to blame for this, because my own writing time is precious now.
That means I am looking for something incredible from my own writing. While I love Court of Dreams, it started as a bit of fun. So did Searching and Witch Hunt. They were never intended to be the greatest novels ever written (though CofD was intended to have a crack at being as funny as humanly possible). Now though, there's a part of my brain insisting that only perfect inspiration will do.
Perfection is a dangerous concept for a writer. A novel is, as Neil Gaiman famously noted in an introduction, a long piece of writing with something wrong with it. Yet so far, I haven't been able to find the imperfect thing that is perfect enough to want to do.