SONOS and RSTP

Hello, I've been reading the forums here and over at Sonos and tryning to figure out the best way to configure these Netgear switches to not have any loops on the network.  In reading the forum, it appears that the Sonos does not support RSTP, so it's been suggested to adjust the RSTP Path costs so that the SONOS don't use their wireless network as the backhaul causing loops.   I'm a bit new to this, so i wanted to see if someone would lend a helping hand and let me know what those settings should look like.  below is an image of the network setup with just the SONOS and Access points depicted. 

In looking at the switches, i see the links to the other switches from the core set to 20000, and the links to the SONOS devices to 200000 (except the one connected to the GS305 since it does not support STP).  I guess my question is what are the correct settings on these ports so that the network stops going haywire. 

Oops, forgot to add all switches running at the most current firmware as of 3 days ago, and for some reason my image does not seem to show...