[Ken Case]

I don't use a Waiting context, myself. What I do instead is to set a future start date for the action, placing it on hold until that start date is reached. This effectively gives me both the desired "Waiting" state, plus a tickler to follow up on the action: if I don't hear back from them by the time the start date rolls around, it pops back up on my active list.

What it doesn't give me is a good way to see all of my "Waiting" actions at once the way assigning it to a specific context would, so while that works for my workflow it might not work for yours.

(In OmniFocus 2, you will also be able to change an individual action's status to "On Hold", so you won't have to make up a future start date in cases where that tickler isn't appropriate.)