For a long time now, the 2.4 GHz ISM band has been, to put it charitably, a swamp. With leakage radiation from microwave ovens, bluetooth, wireless remote controls, and God-only-knows-what-else, it's amazing that 802.11g passes traffic at all.
You'd really rather have people be on one of the 5 GHz UNII bands if you have any choice in the matter. 5 GHz goes a shorter distance and does a poorer job of penetrating walls than 2.4 GHz. If you're on the UNII-1 subband, power limitations further help you not-hear-the-neighbors, and if you're on UNII-2 / UNII-2-EXT (DFS required) you'll discover that it's pretty empty there by comparison, at least for the time being. And there are a lot more channels, 802.11N doesn't take up the whole band... and there's even enough space for 802.11ac, which doesn't exist at all on 2.4 GHz.
Why doesn't this just automatically work? Clients are notoriously bad at choosing 5 GHz if available. Android, Windows, iOS, Mac, it doesn't seem to make any difference - if you have a 2.4 GHz SSID and a 5.x GHz SSID with the same name, there is a lot of client behavior out there to prefer the 2 GHz band on the basis that the power level is higher, which is about the last thing you should be caring about (signal to noise ratio and anticipated throughput would steer things to 5 GHz rather than 2.4 in many cases, but programmers aren't typically RF engineers and so they do don't make the accommodations that would make a client sticky-to-5 GHz.
Ever since the days of 802.11a, there's been a convention of naming SSIDs along the lines of "MySSID-2" and "MySSID-5" so as to indicate to clueful people that there are both a 2 GHz and a 5 GHz SSID available and that they should pin themselves to the correct one.
Recently, I've started naming the SSIDs along the lines of "MySSID" and "MySSID-2". The vast majority of smartphones, tablets, and laptops that are out there today are dual band; they'll see both, while some downrev or low price devices like the current generation Amazon Fire tablet will only do 2.4 GHz; they will see "MySSID-2" but not "MySSID".
The hypothesis here is that people will tend to choose the "first" item they see, which in this case will be the one with no suffix, and that clients, clueful or not, will tend to be steered to the 5 GHz one. A little harmless social engineering to get clients to do what's in their (and our) interest.
Limited testing at a coffee shop seems to support this hypothesis. How about you, want to give this a shot?