In this project, you are required to come up with a planning domain of your own choosing (hopefully different from the existing ones), and experiment with it on one of the existing planners (say FF or AltAlt). Here are the individual tasks.
I would encourage you to think of domains quite different from the ones you have seen. Even if all aspects of your domain cannot be modelled with PDDL, it would be worth finding some abstraction of the domain. Latter you can consider developing a version of the domain with PDDL 2.1.
If your domain requires ADL effects/preconditions (quantified and conditional effects), you may want to develop one version with ADL and one without ADL. (This is standard practice in the planning competitions now--where they give out multiple versions of the same domain).
Here are some papers that describe the efforts of the various authors in converting complex domains into PDDL-like syntax (you don't have to read these at all. Please note that these may or may not be the best ways to model or solve the respective problems.