If you are building up a speaking syllabus from scratch, you need to look at how it will fit into the existing syllabus. You'll need to decide how to link it in: either by topic or by structure.
Personally, I think it's best to match topics as students will have more ideas ready and they'll have easier access to the necessary vocabulary. Linking in with grammatical points might be useful at lower levels where more controlled speaking activities are needed.
You also need to consider whether the focus is on accuracy or fluency and you should remember to incorporate pronunciation practice. Try to get a balance between all three of these.
Some useful books to look at include:
Discussions A - Z (Cambridge University Press). The topics are very accessible, for example: money, love, science. All students will find something to say on these topics. Books are also available for different levels.
Communication Games (Longman) also exist at different levels and provide controlled speaking practice.
Pairwork 1, 2 and 3 (Penguin). Topics can be thought-provoking and so some students can find a lot to say.
Also take a look at Recipes for Tired Teachers (Addison Wesley).
The fact that your students always say "fine" when asked how they are is totally normal. Think about how often people (including yourself and your colleagues)say this in their own language. It's one of our expectations of social situations and so your students are doing what comes naturally.