Sounds like you got a large house. I recommend an Amped Wireless R20000G
I have the R10000
and the coverage is awesome. I got mine for under 90USD at microcenter...
I can stream youtube vids very easily at more then 150 feet away (HD) and SD vids I can play from 215 feet away! and this is outside thru 5 walls!
It's even got QoS settings to make sure you get the B/W you need from the right devices.... so those have higher priority over other people's stuff like smartphones, tablets, etc and your gaming machine or streaming machine gets more B/W then secondary devices in the house. It's very nice. I use it to give extra juice to the xbox and my server.