Whole Home Streaming

I didn't seem to encounter a recent version of this when searching threads, but I apologize in advance if this has been discussed before.
I am out of town (currently in Boston area) for a funeral. My brother in law invited us to his new townhome. He doesn't have an audio system currently in place. The town home is on 3 levels. The previous owners had a Sonos system in the house but apparently it stopped working years ago for unknown reasons. The sellers left all their audio equipment behind in built ins. A receiver, VHS player, and cable box.
My b-i-l would like to do something better than Sonos so he isn't interested
in reviving the current equipment. He was quoted $30,000 from a local high end HT place. He is willing to go to 1/3-- 1/2 of that. He is quite tech savvy but not up to date on audiophilia
My question here concerns the whole home streaming end. i'm a Mac&Dac
guy in my own home and rely on Apple TV to stream from my main two channel system to my two HT systems, but I don't do serious listening in the two HT areas. He intends to do serious listening in the 3 areas. They are:
1) The family room/great room area, where the aforementioned built ins and residual equipment resides.
2) A living room downstairs and across the hall.
3) A Bedroom upstairs.
His Domestic Partner has veto power over any ugly looking stuff in areas one and 3. My b-i-l would like to control everything wirelessly from a tablet and have as much of a wireless connection as possible. He listens to Classical music and some pop, mainly CDs ripped to itunes.
The existing equipment will not be retained.
The main priorities are 1) Simultaneous streaming in the 3 main zones, 2) Sound quality, and 3) as few wires and ugly boxes as possible.

Suggestions?
And can anyone suggest a reasonable HT installation in the Boston area?