The EFF launches a router project

I have a WNDR3800 and I have it set up to have a guest and private network on both 2.4GHz and 5GHz, so that is another possible solution. Unfortunately, devices tend to not support connecting to both frequencies at the same time (and there's no way to distinguish the 5GHz band from the 2.4GHz band in the Android UI either without different SSIDs).