Reading for something other than my degree

My goal is to finish a draft of my paper, something that won't make my supervisor wonder why I've been allowed to continue in the program--sometime in the next week. This goal coincides with our last trip of the summer, a return to visit my sister (and my alma mater's library). And although I'll be trying to get some more research and academic reading done, I plan on treating myself by turning to some fun reading.

Now for the decision: which series to continue? I have four options and no clear winner right now. All of it's fluff reading, most of it is juvenile (as in, I will be heading to the children's section of our library). For all of these, I'd probably bring at least two books with me.

1. This one wouldn't require a trip to the library, but I'm itching to re-read the entirety of Harry Potter. I just saw the 6th movie this week and usually would have already worked through at least the corresponding book, if not the entire series, but it didn't work out that way with this one.
2. One of the trailers before Harry Potter and the Half-Blood Prince was for Percy Jones and the Lightning Thief. I read that book, borrowed from a friend in Toronto, shortly before leaving there. I have not picked up any of the others and had almost forgotten about the series. But it's an enjoyable read and almost on-topic for me, given the presence of the Olympian gods.
3. Then again, there's a series I started fairly recently: Books of Ember. The first book was made into a movie, City of Ember, which Trillian and I saw via Netflix. The movie did not do particularly well, meaning that the remaining books will likely never become movies, but I was intrigued by the ideas and (as is usually the case) found the book even more compelling.
4. Finally, I made it through the second book of the Twilight series a couple months ago. I'm not enamored of the series and have grown to dislike Edward and Bella even more, but I feel almost obligated to power through in case I experience a sudden conversion. (Interestingly, I was checking out an author blog at the time I was reading the second book and she made some reference to some book she'd been reading where she disliked most of the characters and thought the writing was not particularly good, yet she felt compelled to continue. She purposely didn't name names, but I'm convinced she was talking about this series.)

I suspect I know what the general consensus will be, but am still interested to see what people say.