Another way to force your ipad to 5 Ghz without disabling 2.4 Ghz on the WiFi is passwords. (I use passphrases, longer and still easy to remember.) On my airport express, I've setup NoInternetHere and NoInternetHere 5Ghz. for devices that can do the high frequency, I only log them onto the high one. They never get the password for the lower frequency and therefore never look for it. And you can "forget" any WiFi you don't want it to connect to. (Think that's easier on a MacBook.)
Dan will be happy he got the iphones right. I've got a 4S and 5 Ghz isn't an option for it. (Primary reason I keep the 2.4 ghz option available.)