As a quick aside, have you looked into radio controlled multicopter camera setups?
Take a look at the third image on the top row of this guy's site, under the "Photos" heading. Something very "up close & personal" about the wide angle perspective from probably no more than 50 feet altitude, which would require special wavers for a real helicopter and otherwise blow the heck out of the scene. I think those shots are far more appealing than the 1000ft+ shots in your examples. And it's no trouble at all shooting straight down with those things, minus the barf.http://www.multicoptermaui.com
Those multicopter setups are a hard nut to crack, as you can tell from the abundant, relatively artless amateur work around the web. Would take 100's of hours to get one going, unless you spent the money for an off-the-shelf system. But you wouldn't have to hire real aircraft for very many hours to reach the investment cost, and you would have the advantage that you could go to work with a few hours notice and relatively little pre-planning. Downside: I personally predict a significant crash per each 10 hours of flying time. Maybe I'm wrong, but former Chinook crew chiefs like myself are have certain sense about such things.
Whatever you do, just make sure it's not this...http://onebigphoto.com/uploads/2011/11/personal-multicopter.jpg