To answer the original post: I have experimented with a number of suction mounts. The three that I like the best are two from RAM and one that is somewhat ubiquitous, often pitched as a mount for the GoPro.
RAM's original suction cup is a bit bulky for my taste, but has a flat mounting area that takes RAM balls or other things.
http://www.amazon.com/Mounts-3-25in...F8&qid=1405262271&sr=8-1&keywords=ram+suction
I like RAM's newer, less bulky, mount better but it has an integral molded 1" ball, so adapting it to anything else takes some work.
http://www.amazon.com/Mount-Suction...F8&qid=1405262271&sr=8-2&keywords=ram+suction
I like the "GoPro" mount the best, but it is the most difficult to adapt to other hardware.
http://www.amazon.com/Gopromate-Suc...&qid=1405262237&sr=8-5&keywords=gopro+suction
Note that these are all suction mounts that mechanically pull a vacuum underneath the "cup." I think that is essential for a mount that can be relied on. The only times I have had trouble with this type of mount is when I have tried to attach to a windshield with some curve to it. With anything near flat and with a little attention to cleanliness of the mating surfaces, I've found the mounts to be solid.
Re where to mount, on most airplanes I mount my Nexus 7 on the side window. There it is right under my nose so the screen size is effectively larger than a 10" tablet on my knee. Also, it is almost always possible to mount it so that nothing on the panel is blocked and the tablet is well below my sight line so it doesn't reduce "see and avoid" either. There are a few airplanes where I've found the corner of the windshield to be a good place for the suction cup, but of course it has to be fairly flat for reliable attachment.
I usually buy from gpscity.com. I've found them to have good stock, fast shipping, and competitive prices. Just a happy customer, no other interests in their success.