I was looking into which library to use for an upcoming game, and I was looking for the feature lists for SDL and Clanlib. It seems to me that basically Clanlib has what SDL has, but it also has lots of things built in (GUI's, network code, etc.) that you have to hunt around for and compile with SDL. And they both, of course, support OpenGL. It seems like Clanlib has everything SDL has and more. Yet people here seem to overwhelmingly prefer SDL. I'm leaning toward Clanlib, but I'm wondering if there's something I don't know about one, the other, or both. Is there something I'm missing?

It sounds as if you pretty much captured what both libraries are about. SDL is a lot more basic, it basically just gives you a nice interface to the hardware no matter what the underlying operating system is. You'll have to do a lot of things yourself that Clanlib already does for you. I have found Clanlib to be quite well-designed and I prefer to use it, but I think a lot of people like to do all of that themselves as they can do it exactly the way they want it and they will learn more about the implementation of these features.

If you are going to be working alone and you don't want to mess around for a long time just doing very basic things, then I'd suggest Clanlib.