One last thing you can try (I'm pretty much out of ideas here), go into the Wi-Fi settings (Settings>Wi-Fi>(select your Wi-Fi network)>Blue Arrow) and make certain that your iPhone(s) match your iPad's settings exactly. There may be something in there that's different (I have no idea what) that's causing the issue.
Another idea (as my beta tester mode kicks in)...are you trying to download the content over the same means (Wi-Fi vs cell)? If not, download the content using the same connection if you can. If you are already using the same connection, try the other.
It still seems like a internet connection issue to me, thus those suggestions. Again, if you've already tried, disregard.
Thank you again for the help. We think alike, I have tried every possible connection I could think of. Between my home and office, I have three different WIFI networks. I have tried every one of them, and I have also tried both 3G (when it was my iphone 4) as well as 4G with my new iphone 5. I'm pretty certain my ipad table purchases were made with some combination of these networks. In other words I did not purchase all tables in the same location.
I just checked the little blue arrow (which I had not previously checked), everything seems to be in order there.
I think I'll try again while doing a head stand and singing moon river. I can't think of anything else!