The way I work, and I could never find an appropriate application for this beside copy pasting between text files or omnioutliner files, is to review on monday morning the items I need to do this week and assign them to different days of the week (do dates) to balance the week's work load while making sure all the due dates are respected. So being able to build a view by dragging items would be great; for example a partial weeks work load would look like:

Monday total time: 8hours 40 minutes
call Jim for blah 30 minutes
write section x 4 hours
Staff meeting 1 hour
book lab time for wednesday 10 minutes
complete feature X 3 hours

Tuesday total time: 0

Wednesday total time: 4 hours 10 minutes
send notification for next weeks review 10 minutes
Lab testing of feature x 4 hours

Thurday total time:2 hours
Write section y 2 hours

Friday total time: 30 mins
Write weekly report 30 mins

Since some of these items always occur on the same week day (since the weekly report can't be written before enough of the week has passed or the staff meeting is every monday morning at 10 AM), being able to have them reschedule automatically would be great. Having a function to automatically make an initial distribution of the items due this week would also help.

The total time on each day would of course be calculated automatically.

Having such a view allows to quickly answer the question "Can you handle this emergency?" since you then know what's on your schedule and can replan quickly around it when an item will be done. It also allows to look a little bit ahead of time and work on an item early that is not necessarly the next "@office" to do item. For example, if its 4h30pm, I am too tired to code, but I could draft that important e-mail I have to send tomorow but might not have the time to write then. It also allows to see whats ahead this week or the next (and all the little work items that are too small to be put on an official project plan but do end up eating time) and say "Oh boy!, my schedule friday is way to busy, maybe I should work an extra half hour this week to be able to leave not too late for that weekend getaway".

I know this is not GTD culture as per say, but it could easily be a third view of the items (by do date). In perspective, Omnifocus should be a tool to make it more easy for the user to keep focussed and remain productive regardeless of events, location or workload while making sure no items fall through the cracks.