I think I've sorted out a cheap, yet functional solution, but I want to make sure that it will work...
I've found a
Yamaha HTR-5250 on Craigslist for next to nothing.
It is a 5.1 receiver with a Pre Out.
I will run the Channel A speakers to the Kitchen and the Channel B Speakers to the Dining Room (and the Sub to the Sub, of course) - decided I don't need to adjust the Dining Room volume separately.
I can use the Pre-out to add an amp to power the outdoor speakers at a later date.
For Airplay, I'll just get an Airport Express or Apple TV and use one of the inputs on the receiver.
Does anyone see a problem with this set up?
Thanks to everyone for their help.