I have enabled the 5GHz network & used the same SSID as the 2.4GHz network. That way my 5GHz enabled devices switch to use the faster network automatically, but the non-enabled 5GHz devices remain on the 2.4GHz network. This way you'll get the best connection your device/s can handle.
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^continued from my post above;
From the top of my head, your 5s & iPad mini will exploit the 5GHz network & your iphone 4 & iPad v2 will use your 2.4GHz network.
I have a similar set of devices & this set up works well for me.