Also, placement of router is very important. Most people have their wifi in the basement, where their cable/phone line comes in, spending some time, and running a physical wire somewhere to the center of the living space, setting up router on a shelf or a table will go a long way in propagation. I have mine setup in the center of my bungalow, and I have 5Ghz WiFI reaching from my driveway to the backyard, no issues, and never any hickups.
Also, if you pick a high end router (Like ASUS 86U with merlin) -> you get some proper Wifi diagnostic tools built in, like number of packet retransmits, bad FCS, etc, which will help you diagnose your issues.
Multiple people on the same band is not as big of an issue as many claim it is. 5Ghz (no B/G legacy frames), and 80MHz bandwidth ensures that most traffic is very short in actual airtime. Not perfect, but, it is orders of magnitude better than 2.4Ghz, despite there being really only 2 80MHz channels available. There is also, channel 165, which is 20Mhz only, but rarely occupied.