It would great to only need one app opened for all of the daily planning. Good Task is really close to that for me.
One feature on the Apple Calendar that is missing and is so useful is it shows what the time is currently in relation to appointments. Makes a great visual to see how close am I to the next appointment with little thought and I can keep working on a task as that time gets closer.
Adding something like that to the calendar events would make Good task my only app open to keep track of my day while I worked.