Distributed audio doesn't mean bad audio, but your dining room isn't a audiophiles dream. You also would be completely incorrect in assuming you can't get quality audio throughout your home. You just can't get a perfect audiophile room in every corner of your home.
Proper wire gauge, and proper amplification, with good quality analog cables delivers 90%+ of the quality you get from a $20,000 system out to your rooms throughout your home. If you want 'good' or better audio in those rooms, then those rooms would need the same care and attention for audio that your primary listening room would get.
That's feasible, but not realistic.
The fallback position becomes a question of how you intend to use the audio, and what your real expectations for quality are, or need to be.
A bunch of kids in the home... Do you want audio throughout for parties? Background music for events in your home? Christmas music everywhere? Non-critical listening? Well built speakers that can survive a few teenage parties with the audio cranked up?
Getting decent or even good audio out of ceiling speakers isn't impossible, but it depends on what your definition of 'good' is, and what rooms they go into.
My most used speakers in my home which has about 20+ zones of audio, are:
1. Main family room speakers (floor standing 3.1 audio setup)
2. Kitchen speakers - playing the same as the family room, usually the TV
3. Speakers in my garage/speakers out back
4. Theater surround setup, for movies on the big screen.
5. Bedroom speakers for local televisions (several rooms)
Now, my kids are still a bit younger, but I expect the speakers in the dining room and living room and other rooms may get used occasionally for parties, but that's about it. That's okay, they were relatively inexpensive speakers.
I personally love just throwing on my Pandora mix through my Apple Airport and listening to music as I'm working on cleaning up the house. It's background music, but I turn it up a bit and it certainly is like driving with your car stereo up. It's not perfect, but it is fun, and it does fill the space very nicely. It achieves a goal.
When I sit down in my family room and watch a movie, the speakers in there have their purpose, but the rest of the speakers also have their purpose.
They aren't 'jammed in'. They are designed to be part of a quality setup. If all you want to invest in is 'jammed in', then those zones will take more of a hit in quality.
My setup thread:
http://forums.audioholics.com/forums/threads/so-here-we-go-24-a-v-zones-w-10-sources.83272/