In wall surrounds and rears & in ceiling Atmos to pair with S60 fronts?

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I've decided I love the S60s and will be using for fronts but plan on doing in wall for surrounds and rears as well as 4 in ceiling atomos speakers. I have two 12" PSW505 subwoofers I will be using and will be using Polk S30 or Klipsch RP-504C for the center.

Any suggestions on what I should look at? I'm willing to spend up to $150ish per speaker (amazon/ebay prices) but I don't want to waste money & I'm wondering if I'll be able to tell the difference if I go with the cheaper ones on Amazon that all have great reviews and go for $40 to $75 per speaker given that they will be used for surrounds and rears. (eg. Polk RC85i/RC80i, Polk V60, Micca M-8S, Monoprice Caliber, etc)

Also interested in opinions on if I should build boxes for them. I'm reading a lot of competing recommendations online.

Thanks in advance!