Here's an app from the Mac App store that offers an interesting twist:
SmartDay is different from all other calendars because it is a truly integrated organizer – it uses our SmartTime™ logic to schedule tasks for you directly into the free time in your day.
This is for folks who like to "plan" their days and stagger their tasks throughout the week.
At the moment, I just look at my calendar and look at my appointments that I have to keep. Then when I don't have an appointment, I look at my "Today" perspective in OmniFocus (basically a context perspective with Due soon & Flagged actions).
I generally don't like to "schedule" a task because there might be times when I'm too brain dead and I'll just move that task to another time and work on something else based on my energy levels, context, or time duration.
But for those who want to schedule tasks, this might offer a different solution.
Hopefully OmniFocus can start breaking away from the outliner mode only view (as it exists now) and start offering other types of views such as the forecast view and something like SmartDay.
I saw Daylite 3.x's interface and they were stuck in that typical outline view. It made it look and feel look a database. The new Daylite 4's user interface starts to break away from that modal feel. Unfortunately, it's still bug-ridden and not really ready for prime-time use.