This is a personal favorite of mine. Different jobs have plenty of interplay so you're encouraged to do a lot of different tasks, but which ones you do, what order you do them in, and how much you should do them is left up to the player and is a great puzzle to try to optimize. One completion shouldn't take much more than a few days, but if you want to go for 100% completion it is a long haul (but has new content in the form of jobs on each loop).