This question has been bopping around in my head the past few weeks. I see my writing work as involving three elements -- design, creation and editing. If I put then in order of my enjoyment, it would look something like this:
I definitely enjoy the creative process the most -- musing each day about how I will craft the next scene in the story I've already designed. That's when I come up with those clever pieces of dialog, or those brief descriptions telling as much in their omissions as they do in their revelations, or the sequences of actions as they play out in my mind.
I've always enjoyed plotting as well, and think I'm pretty good at taking the big picture down to the details. Plot development is where I think through the sequence of scenes, the how it happens (for example: The character needs to be involved in a stock trade that will later look like insider trading, but in reality he will be innocent -- how do I make it work). It is also the time for developing misdirection and red herrings -- the elements that make the outcome of the story a surprise, or at least a partial surprise.
Editing is a bit tougher. It involves reading and correcting everything from broad strokes (move that scene from the night club to a museum, combine characters A and B) to fixing grammar and punctuation. The problem I run into here is what I call story fatigue: by the third or fourth editing pass, I'm sick of the story, and just want it to be finished. I combat this by leaving projects to ferment for at least a month between editing passes, but it only helps a little.
Designing the characters, and specifically writing character profiles, is something I just plain don't like much. It's okay for three or four main characters, but when I get to the secondary characters, it just becomes a slog. I have to force myself to stay on task using close in milestones and little rewards. Fortunately, it is probably the least time consuming task in the process (at least the way I do it!).
If I thought about where the time is spent, however, it looks more like this:
No doubt editing work takes at least three or four times the amount of time the original creation work did. I don't know of anyone has any tips to make the editing process more interesting or to stave off story fatigue, but if you do -- please post them as comments here!