Any more than 2.5" leveling will trash your front end parts. I don't even want to go that high, because my angles are flat and I like them that way. I considered a diff drop, level, and airbags(rear, for towing) to raise the whole truck a little. But I decided I wouldn't really get anything from the height, other than making it hard to jump in the bed.
Many people say when you get a lift, get a full 6" suspension lift, because you'll want it eventually anyways. If I wanted a lot of height, that's what I'd do. But there are more than a few trucks with a level and body lift with very happy owners.