Six speakers limits you to Sonance-Sonos ones, all other 8 Ohm ones have a limit of four.  You can get impedance matching speaker controllers to exceed these limits.

• Your speakers’ power rating should be at least 125W for 8 ohm speakers, and at least 200W for 4 ohm speakers. Do not connect speakers rated at less than 4 ohm.
• Amp can drive speakers with nominal impedance above 4 ohms. Two pairs of 8 ohm speakers wired in parallel are also supported. Don’t wire your speakers in series because it will result in poor sound quality.

Are you sure you want ceiling speakers, while pretty good for background sound they aren’t great at providing a stereo image and it can sound a bit odd with the sound coming from up there.

An alternative is the wall mounted Sonance-Sonos speakers, mounted at ear level they are usually better for listening.

https://www.sonos.com/en-us/shop/architectural  (if you have a discount coming note the sets that count as one item for discounts)

Handy chart, one wire size larger isn’t expensive so I’d do that.

https://support.sonos.com/en-us/article/choosing-a-speaker-wire-gauge

Appreciate the response - thank you! I think I’m still leaning towards ceiling speakers for the large space… however, I think you’re right… for smaller rooms, I may just make do with bookshelf speakers… or perhaps in-wall, but certainly not ceiling. 
 

Starting off with a pair of 100s isn’t a bad idea, try them in your areas to get an idea of what your sound will be. They are easy to move around and position, aside from needing temporary power connections. Once done testing just find them a permanent room.

I have a similar question to @Redcloud75013 in terms of a large room and number of speakers.

Our room will be about 800 sq ft and also has living/dining/kitchen areas in a great room (this will be new construction). The room is 24 ft wide, living area at the front and then dining and kitchen side by side behind that. I’m going to be getting the Sonance ceiling speakers with the Amp (we have windows on the walls in front of the living area and running back to the dining area).

My question is whether to put in 4 or 6 speakers. One pair would go at the front of the room (over the living area). Another pair would be toward the back of the room, over the dining area. My questions:

• Would this arrangement provide enough sound for the kitchen area or should I put a third pair in the kitchen?
• If I put another pair in the kitchen, do I potentially run into phase interference issues with the dining area pair? The kitchen set would likely be installed longitudinally (looking down the room), while the living and dining area sets would be lateral.

We have a similar setup in our current house, where the living and dining areas are side by side (with a set of in-wall speakers on the living area side) and kitchen is somewhat separated in another room next to the dining area (with ceiling speakers). This provides good sound in all these areas, but ceiling speakers are appreciated in the kitchen due to more noise when cooking.

I’d be really tempted to go with three pairs run in Mono mode. Space them away from the walls and each other, looking for as even as possible sound levels throughout your space.

With that setup you are going to be aiming for more even sound, not stereo imaging.