i'm looking to upgrade my house Wifi points.  I've got cabling run around the house and PoE from my switch. Currently using some old Cisco wall mounted access points (WAP121).

The house isn't large, but it's got some steel framing running up through it, and a thick concrete slab between basement and ground (with steel rebar - nothings getting through that).  I want wifi coverage in every room and on roof above (so can control IoT devices that aren't exposed beyond local network) 

I've got wall mounted (near ceiling level) ethernet points where the red dots are so i'm either mounting wall mount units or wall mounting ceilings units (and the smaller the better for aesthetics) As i understand it the transmission BEHIND both types of units is poor but i don't get a feel for how poor - it only need to reach at most in the basement c4m through a two plasterboard walls.  

Any thoughts?