I always think these look nice with all the colours. 100% generic and nothing special but still a learning exercise. Squashing everything down to get the PCB fab price down meant a load of itterations. I could squeeze it a bit more getting rid of the last of the DIL devices but I have them in my parts drawer and I am only building a few PLCs.
A couple of LEDs thrown in so I can use them for blink type sketches and also visual feedback. I can flash green for a routine being successful and coded red to show error codes, Quick, dirty and simple way when peering underneath the baseboard wondering why something is not working.
+++ Extra thought I have done a copper pour to get a ground plane for the ground net. 16MHZ is pretty low frequency but this might help in terms of noise etc.