[whpalmer4]

There are a number of approaches that can be used.

If you really want to have a priority field, and don't use the duration field, repurpose it as a priority value, with the smallest values being the highest priority. Now you can use the sorting and grouping operations on the "priority" field.

Another approach is to use the implicit prioritization that OmniFocus provides. After all other sorting is done, OmniFocus shows items in the order they have in the sidebar. If you move the more important projects to the top of the sidebar, their tasks appear earlier in your lists.

Be ruthless about putting projects on hold, or setting future start dates. If there isn't any realistic chance you'll get to something this week, don't have it cluttering up your lists. You can always take something off hold if you get everything on the top priority list done! Use the Review feature to keep tabs on all of your projects to shuffle them on and off the active lists. If you have projects or single action lists stuffed with independent actions, select a group of those actions that you won't get to right away, bring up the inspector, and set a new future start date. As long as they aren't repeating actions (where preserving the original start date might matter) it doesn't matter if they could have been started yesterday or three months ago if you won't be able to tackle them before next week due to your current workload.

You can use all of these tactics simultaneously.