I had to respond to Misty at The Book Rat about stand-alone books vs. books in a series. I totally agree that with some books you get the impression that it was not meant to be a series. The only thing that really drives me nuts is when there's a cliffhanger randomly thrown in at the end of a book and it's obviously a ploy to get you to buy the next book when it comes out. That's the only thing that bothers me about series, when it's an obvious addition to an already wrapped-up story. Then there's series that are mainly the same story over and over again. The Stephanie Plum series by Janet Evanovich comes to mind. Essentially, with every book, readers are going to expect certain things to happen. They're funny and entertaining and readers know what they're gonna get when they pick it up. I've read a couple of these books, and I have to say, they are hilarious and entertaining, but really, I would never read the whole series.
I will say, I do have a preference as to which genres I feel do better in a series vs. a stand-alone book. I find that, often a series works best when it's fantasy or dystopian or paranormal. I guess maybe it's because there's so many things that can happen and the fantasy world is so intriguing that I'd gladly return to it again and again. Contemporary fiction has to be really great to keep me wanting more after I've already read the first book.
Having said that, I have found few series that disappoint. Whether or not most series are written with that intent in mind or whether it's steered in that direction by the publisher, I have found that most series I have read (or are reading) are really great. I can't say whether I prefer a stand-alone over a series or vice versa, because it all really depends on the book. If it's well written and I'm really into the story, I would love reading a 2nd and 3rd book. Some even turn out to be better than the first. I mostly enjoy the experience of getting involved in a story and in the characters' lives and when I'm finished with a 1st book in a series, I have fun wondering what's going to happen next and that I have to wait (usually) to find out. I like being able to start a 2nd or 3rd book knowing what's already happened, already being familiar with the setting and the characters. And, I guess I'm weird in that I actually like the anticipation of the next book in a series to come out. :)