What Doc said. please keep in mind as you design your wifi setup that there are a number of unexpected things that block wifi signals. Some problems to be aware of include:
Mirrors (the metal back blocks wifi signals 100%)
Plaster / lath. Metal lath is a metal screen, and seriously attenuates wifi signals.
Stone. Especially ferrous stones. Granite, for example.
Metal backed insulation. That aluminum foil backed stuff.
Aluminum siding.
Kitchens with active microwave ovens (
great for nagging 'intermittent" problems. )
When I do a residential wifi survey I set up an access point in a central spot of the house and walk around 'sniffing' to see where I can see it. I had one house that we had to put in four AEBS on an ethernet backbone. I personally prefer the ethernet backbone if the cost to run the cable isn't an issue, because it's more reliable and you end up with a futureproofed distributed high speed network.
I've used omni antennae, which work well, but have their own issues.