Challenge Day 10: Choosing the Next Book

How do you choose what book to read next?

So how I choose my next book is rather a random process. I don't actually keep a book list - well, I do, but it's all in my head. So it's not like I go down the list checking off books.

The easiest decision is if the book I just finished is part of a series - I just get the next book! However, if the book I finished is not in a series, or the library doesn't have the next book (remember, most of the time I get books from the library instead of buying them), or if the next book hasn't come out yet, the decision is a little harder.

The first book from my mental TBR list that pops to the forefront of my mind is usually the best contender for Next Book. I roll that option around in my head, and if nothing else comes to mind in the next ten minutes, I head to the library. If walking through the shelves doesn't produce any more results, that first book is it and I take it out.

That's my usual routine, barring three exceptions:
~I am tired of a particular genre/style/author. If so, and the book that comes to mind first is of the same genre/style/author, I have to do a deep search into my mental TBR list for something drastically different. For example, after reading the first four books of Harry Potter in less than a week (and yes, Harry Potter is great, but there are limits), I had to take a break. So I read five Jane Austen books the next week (which was also great, but then I promptly returned to Harry Potter).
Generally, this exhaustion of a genre/style/author happens when I speed through books, as in the aforementioned example. This usually happens in the summer, when I'm not just reading a few chapters in between homework assignments. I probably get through twice as many books in the summer as I do in the rest of the year.
This exception may also happen after I have read a very long book - Les Miserables, for example (and yes, Les Miserables is also an awesome book, but again, Very Long). After reading this, I had to go for something light - I ended up with Jasper Fforde's Thursday Next books.

~One of my friends recommended something and is bugging me to read it, which usually means that title is in the forefront of my mind anyway. One example is from back when I was eleven or twelve and my friend kept telling me how wonderful Gone With the Wind was. I told her I would read it next - and I did, except the book I was reading at that point was The Count of Monte Cristo, so it was quite a while before I got to it. (That reminds me - it's been a while since I read Gone With the Wind.)

~I need to read something for a class. This is similar to the second exception. If my English class requires me to read, say, The Great Gatsby (for the fourth time), that's my next book.

There's my book-choosing process!
Do you have one that's different? Or are you as random as I am?

~Sophia