Most 2 zone 7 channel receivers allow you to run 5.1 in the main room and stereo music in zone 2 using the extra two amp channels. What I would do if I was you was really think about what your sources are going to be and how you really plan to use the system. Is your music mostly on an iPad device? A PC server? Do you mostly listen off of CDs? How do you really see using the patio and kitchen speakers. You mentioned mostly background music.
Here is my suggestion.
Get a good 2 zone, 7channel receiver, like the Denon, for the living room. Whatever you get, make sure it has preouts for zone 2. Run the speaker wires for the patio and kitchen to boxes on the wall for volume controls, then to the area where the living room receiver is. Hookup one set of speakers, does not matter which, to the extra channels on the back of the receiver. Then get a cheap 2channel amp, like this one:
And hook up the other two speakers to that amp and then connect it to the preouts on the receiver.
Hook up all your digital sources (Satellite/cable TV, BDP, etc.) with extra analog cables to enable the audio to go to zone two.
Now you can play the same music through all 9 speakers if you set the zone 1 and 2 inputs the same. Or, watch TV, movies, play Xbox whatever, in the living room and listen to a different source outside or in the kitchen.
The only reason to get a 3 zone receiver is if you want the patio, kitchen and living room to play 3 separate sources at once.
Then, just get a decent 5.1 receiver for upstairs. If both receivers are connected to your Internet, you should be able to play music from a computer on both, or from a tablet via Aiplay. Get whole home DVR for TV watching and you are all set.
You would still need to move physical media like a BluRay or CD from the living room to the bonus room and vice versa, but all your digital and streaming sources should be accessible from both Internet ready receivers.