Fly with an iPad lying in your lap for about 15 minutes and you’ll wonder if there is a better way. The thing is basically terrific in the cockpit, but its, how shall we put this, big. Or at least big enough it covers the paper pad youre used to having on your thigh, or big enough in flops off your knees when you want it to stay put. But big also means you might want it out of your lap, and thats the drawback with most of these iPad kneeboards. Sometimes you want a screen thats ready for the glancing, such as when flying an instrument approach, and other times you just want it out of the way where it wont get its screen scratched. 
Simplicity Rules
To that end, any consumer case that wont slip off your lap could be all you need. (We have a $25 Bear Motion case that does the trick just fine.) A bit of Velcro may be handy if you want it to stay just so on top of your current kneeboard.
Another option is the MyClip from Tiet. This is just a leg strap with two padded clips on elastic. The clips grab either side of the iPad-either portrait or landscape-and hold it securely. However, its not so tight that you cant tilt it quickly to get a non-glare viewing angle. If you don’t need the other trappings of a kneeboard (pen and paper, pockets for small items) then this is our recommendation. My Clip was designed for an iPad without a case, but you can make it work with some cases (including that Bear Motion), albeit a bit less securely.
At $40, the MyClip is pricey for such a simple gadget, but it works well. Its leg strap is a bit short, so thick legs might need an extender. We tried taking a case with a loop, like the HandStand, and hacking our own leg strap. It worked … sort of. Worth a shot if your case has such a loop for attachment.
The other plus of a setup like this is you can quickly don it or pull it off as necessary. If you want a real pad on your leg as well, though, you might do better