[colicoid]

The need for a today screen arise when you have many active tasks for the currently available contexts (such is the case for me at work).

Assuming you are trying to stay close to GTD:

The above approach only works for real so called "hard" due dates.
If you want a today view with stuff that "you would like" to get done today but that doesn't necessary "have to be" done you have to pick a different approach.

One way would be flags. Anything that should be on the radar for you today or in the near future could be flagged.

Antoher way is to organize the review dates so that the tasks you might want to work on today shows up under today in a daily review. You basically live in the review mode and knock off tasks.

Perspectives could of course be set up for quick access to all of this.

Another approach is to be very aggressive with what projects are set to on-hold. Instead of doing weekly reviews you will have to do daily reviews to make sure that the stuff you want to work on today is active. Almost everything else is on-hold.