[whpalmer4]

Assuming the project is of a large enough scope to merit doing so, brainstorm in OmniOutliner, build the overall plan/schedule in OmniPlan, use OmniFocus to execute the tasks.

You can open an OmniOutliner file in OmniPlan, though the changes you make in OmniPlan will not propagate back. Carrying the tasks over to OmniFocus is a bit trickier. For one thing, OmniFocus doesn't understand the full set of dependencies used by OmniPlan: Start->Start, Start->Finish, Finish->Start, Finish->Finish. OmniPlan also doesn't directly export to OmniFocus. You can use OmniOutliner as an intermediate file format that both understand, but OmniFocus misinterprets duration values when you import the file, though the outline structure will be correct. There's a lot of room for improvement here, but the good news is that the elves have apparently been hard at work on those improvements!