Probably any sized IT company will come in and do a wifi assessment nowadays. I know Microserve out here in Vancouver will do that. More for businesses and AP placement but I am sure they have a scaled down version.
But, in a house if you cannot physically run wires to your desired location a good repeater or mesh system should work. Or try one of those gadgets that lets you send your connection down the electrical lines. Never used one but I have heard they work fairly well.
|